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TABLE OF CONTENTS

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The information in this prospectus supplement is not complete and may be changed. A registration statement relating to these securities has been declared effective by the Securities and Exchange Commission. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities, and we are not soliciting offers to buy these securities in any state where the offer or sale is not permitted.

Filed pursuant to Rule 424(b)(5)
Registration Statement No. 333-212713

SUBJECT TO COMPLETION, DATED MARCH 21, 2017

PRELIMINARY PROSPECTUS SUPPLEMENT
(To Prospectus dated September 12, 2016)

              American Depositary Shares

LOGO

Representing            Ordinary Shares

$        per ADS

        We are selling            ordinary shares in the form of American Depositary Shares, or ADSs. The ADSs will be evidenced by American Depositary Receipts, or ADRs, and each ADS represents the right to receive 6 ordinary shares.

        We have granted the underwriters an option to purchase up to            additional ADSs.

        The ADSs are listed on The Nasdaq Global Select Market under the symbol "ADAP." On March 20, 2017, the last reported sale price of the ADSs on The Nasdaq Global Select Market was $4.62 per ADS.

        We are an "emerging growth company" as that term is used in the Jumpstart Our Business Startups Act of 2012 and, as such, have elected to comply with certain reduced public company reporting requirements.



        Investing in the ADSs involves risks. See "Risk Factors" beginning on page S-4.

        Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.



 
  Per ADS   Total
Public Offering Price   $           $        
Underwriting Discount(1)   $           $        
Proceeds to Adaptimmune (before expenses)   $           $        

(1)
We have agreed to reimburse the underwriters for certain expenses incurred with this offering. See "Underwriting."

        The underwriters expect to deliver the ADSs to purchasers on or about                    , 2017 through the book-entry facilities of The Depositary Trust Company.



Joint Book-Running Managers

Citigroup   Cowen and Company   Leerink Partners



   

                    , 2017


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TABLE OF CONTENTS

 
  Page  

PROSPECTUS SUPPLEMENT

       

Enforceability of Civil Liabilities

    S-i  

About This Prospectus Supplement

    S-i  

Special Note Regarding Forward-Looking Statements

    S-ii  

Prospectus Supplement Summary

    S-1  

The Offering

    S-3  

Risk Factors

    S-4  

Use of Proceeds

    S-6  

Dilution

    S-7  

Directors, Executive Officers and Corporate Governance

    S-8  

Taxation

    S-30  

Underwriting

    S-39  

Legal Matters

    S-45  

Experts

    S-45  

Where You Can Find More Information

    S-45  

Incorporation By Reference

    S-45  

 
  Page  

PROSPECTUS

       

About This Prospectus

    1  

Where You Can Find More Information

    1  

Incorporation By Reference

    2  

The Company

    3  

Forward-Looking Statements

    4  

Risk Factors

    6  

Use of Proceeds

    7  

Description of Share Capital

    8  

Description of American Depositary Shares

    25  

Plan of Distribution

    36  

Legal Matters

    38  

Experts

    38  

Service of Process and Enforcement of Judgments

    38  



ENFORCEABILITY OF CIVIL LIABILITIES

        We are incorporated under the laws of England and Wales. Some of our directors and officers reside outside the United States, and a substantial portion of our assets and all or a substantial portion of the assets of such persons are located outside the United States. As a result, it may be difficult for you to serve legal process on us or our directors and executive officers (as well as certain directors, managers and executive officers of the finance subsidiaries) or have any of them appear in a United States court. There is doubt as to the enforceability in the United Kingdom, either in original actions or in actions for enforcement of judgments of U.S. courts, of civil liabilities predicated on the U.S. federal securities laws.


ABOUT THIS PROSPECTUS SUPPLEMENT

        This document is in two parts. The first part is the prospectus supplement, including the documents incorporated by reference herein, which describes the specific terms of this offering. The

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second part, the accompanying prospectus, including the documents incorporated by reference therein, provides more general information. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. Before you invest, you should carefully read this prospectus supplement, the accompanying prospectus, all information incorporated by reference herein and therein, as well as the additional information described under "Where You Can Find More Information." These documents contain information you should consider when making your investment decision. This prospectus supplement may add, update or change information contained in the accompanying prospectus. To the extent that any statement we make in this prospectus supplement is inconsistent with statements made in the accompanying prospectus or any documents incorporated by reference therein, the statements made in this prospectus supplement will be deemed to modify or supersede those made in the accompanying prospectus and such documents incorporated by reference therein.

        You should rely only on the information contained or incorporated by reference in this prospectus supplement, the accompanying prospectus and in any free writing prospectuses we may provide to you in connection with this offering. Neither we nor the underwriters have authorized any other person to provide you with any information that is different. If anyone provides you with different or inconsistent information, you should not rely on it. We are offering to sell, and seeking offers to buy, ADSs only in jurisdictions where offers and sales are permitted. The distribution of this prospectus supplement and the offering of the ADSs in certain jurisdictions may be restricted by law. Persons outside the United States who come into possession of this prospectus supplement must inform themselves about, and observe any restrictions relating to, the offering of the ADSs and the distribution of this prospectus supplement outside the United States. This prospectus supplement does not constitute, and may not be used in connection with, an offer to sell, or a solicitation of an offer to buy, any securities offered by this prospectus supplement by any person in any jurisdiction in which it is unlawful for such person to make such an offer or solicitation.

        Unless otherwise indicated or the context otherwise requires, "Adaptimmune," the "Group," the "Company," "we," "us" and "our" refer to Adaptimmune Therapeutics plc and its consolidated subsidiaries, except where the context otherwise requires. "Adaptimmune" and "SPEAR" are registered trademarks of Adaptimmune.


SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

        This prospectus supplement, the accompanying prospectus and the financial statements and other documents incorporated by reference in this prospectus supplement may contain forward-looking statements that are based on our current expectations, assumptions, estimates and projections about us and our industry. All statements other than statements of historical fact in this prospectus supplement, the accompanying prospectus and the financial statements and other documents that we incorporate by reference in this prospectus supplement are forward-looking statements.

        These forward-looking statements are subject to known and unknown risks, uncertainties, assumptions and other factors that could cause our actual results of operations, financial condition, liquidity, performance, prospects, opportunities, achievements or industry results, as well as those of the markets we serve or intend to serve, to differ materially from those expressed in, or suggested by, these forward-looking statements. These forward-looking statements are based on assumptions regarding our present and future business strategies and the environment in which we expect to operate in the future. Important factors that could cause those differences include, but are not limited to:

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        Additional factors that could cause actual results, financial condition, liquidity, performance, prospects, opportunities, achievements or industry results to differ materially include, but are not limited to, those discussed under "Risk Factors" in Part I, Item 1A of our Annual Report on Form 10-K for the period ended December 31, 2016, which is incorporated by reference herein, as updated by our other SEC filings filed after such Annual Report. Additional risks that we may currently deem immaterial or that are not presently known to us could also cause the forward-looking events discussed in this prospectus supplement, the accompanying prospectus and the documents

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incorporated by reference not to occur. The words "believe," "may," "will," "estimate," "continue," "anticipate," "intend," "expect" and similar words are intended to identify estimates and forward-looking statements. Estimates and forward-looking statements speak only at the date they were made, and we undertake no obligation to update or to review any estimate and/or forward-looking statement because of new information, future events or other factors. Estimates and forward-looking statements involve risks and uncertainties and are not guarantees of future performance. Our future results may differ materially from those expressed in these estimates and forward-looking statements. In light of the risks and uncertainties described above, the estimates and forward-looking statements discussed in this prospectus supplement, the accompanying prospectus and the documents that we incorporate by reference in this prospectus supplement might not occur, and our future results and our performance may differ materially from those expressed in such forward-looking statements due to, inclusive of, but not limited to, the factors mentioned above. Because of these uncertainties, you should not make any investment decision based on these estimates and forward-looking statements.

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PROSPECTUS SUPPLEMENT SUMMARY

        This summary highlights selected information contained elsewhere in this prospectus supplement, the accompanying prospectus and in the documents we incorporate by reference. This summary does not contain all of the information you should consider before making an investment decision. You should read this entire prospectus supplement and accompanying prospectus carefully, especially the risks of investing in our ADSs discussed under "Risk Factors" beginning on page S-4 of this prospectus supplement, along with our consolidated financial statements and notes to those consolidated financial statements and the other information incorporated by reference in this prospectus supplement.

Overview

        Adaptimmune is a clinical-stage biopharmaceutical company focused on novel cancer immunotherapy products based on its proprietary SPEAR T-cell platform. We have developed a comprehensive proprietary platform that enables us to identify cancer targets, find and genetically engineer TCR, and produce TCR therapeutic candidates for administration to patients. The Company engineers TCRs to increase their affinity to cancer specific peptides in order to destroy cancer cells in patients. Adaptimmune has Phase 1/2 clinical trials ongoing with our NY-ESO and MAGE-A10 SPEAR T-cells and during 2016 opened two additional INDs for our AFP and MAGE A-4 SPEAR T-cells. Our NY-ESO SPEAR T-cell has shown promising initial results in clinical trials with a 50% response rate and 18-month median survival rate reported in synovial sarcoma (a solid tumor) and a 91% response rate at day 100 post autologous stem cell transplant in multiple myeloma. The NY-ESO SPEAR T-cell has shown a promising tolerability profile to date in all clinical trials. Our NY-ESO SPEAR T-cell therapy has breakthrough therapy designation in the United States and has also received orphan drug designation from the FDA and European Commission for the treatment of soft tissue sarcoma. The EMA has also granted PRIME regulatory access for the Company's NY-ESO SPEAR T-cell therapy for the synovial sarcoma indication. We expect further clinical data during 2017. In addition, we continue to use our SPEAR T-cell platform to identify further target peptides which provide additional coverage for any existing indications or which show high expression in specific cancers. We have identified over 30 intracellular target peptides and have 12 research programs evaluating these peptides. The NY-ESO SPEAR T-cell program is subject to a collaboration and license agreement with GSK under which GSK has an option to obtain an exclusive worldwide license to the NY-ESO SPEAR T-cell program. In February 2016, the GSK Collaboration and License Agreement was expanded to accelerate the development of the NY-ESO SPEAR T-cells towards pivotal trials in synovial sarcoma, as well as the exploration of development of NY-ESO SPEAR T-cells in MRCLS. The amendment also provides the opportunity for up to eight combination studies using NY-ESO SPEAR T-cells. The Company achieved development milestones under the GSK Collaboration and License Agreement of $17.4 million in the year ended December 31, 2016.

Corporate Information

        Our registered and principal executive offices are located at 101 Park Drive, Milton Park, Abingdon, Oxfordshire OX14 4RY, United Kingdom, our general telephone number is (+44) 1235 430000 and our corporate website address is www.adaptimmune.com. Our website and the information contained on or accessible through our website are not part of this prospectus supplement. Our agent for service of process in the United States is our subsidiary, Adaptimmune LLC, located at 351 Rouse Boulevard, The Navy Yard, Philadelphia PA 19112, United States. Since May 6, 2015, our ADSs, which each represent 6 ordinary shares, have been listed on The Nasdaq Global Select Market, or Nasdaq, under the symbol "ADAP."

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Implications of Being an "Emerging Growth Company"

        We qualify as an "emerging growth company" as defined in the JOBS Act. An emerging growth company may take advantage of specified reduced reporting and other burdens that are otherwise applicable generally to public companies. These provisions include an exemption from the auditor attestation requirement in the assessment of our internal control over financial reporting pursuant to the Sarbanes-Oxley Act of 2002.

        We may take advantage of these provisions for a period of five years following the completion of our initial public offering (2020) or such earlier time that we are no longer an emerging growth company. We would cease to be an emerging growth company if we have more than $1.0 billion in annual revenue, have more than $700 million in market value of our ordinary shares held by non-affiliates or issue more than $1.0 billion of non-convertible debt over a three-year period.

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THE OFFERING

ADSs offered by us

                ADSs (with each ADS representing six ordinary shares).

ADSs outstanding after the offering

   

Ordinary shares outstanding after the offering

   

Underwriters' option to purchase additional ADSs

 

We have granted the underwriters an option to purchase up to an additional              ADSs from us within 30 days of the date of this prospectus supplement.

Depositary

 

Citibank, N.A.

Use of proceeds

 

We intend to use the net proceeds from this offering to advance our wholly-owned pipeline of SPEAR T-cell candidates through clinical trials as well as for other general corporate purposes. See "Use of Proceeds."

Risk factors

 

You should read the "Risk Factors" section of this prospectus supplement and in other documents incorporated by reference into this prospectus supplement and the accompanying prospectus for a discussion of factors to consider carefully before deciding to purchase our ADSs.

Nasdaq Global Select Market Symbol

 

ADAP

        Unless otherwise indicated, all information in this prospectus supplement, including information relating to the number of ordinary shares to be outstanding immediately after the completion of this offering:

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RISK FACTORS

        Our business, and an investment in the securities, is subject to uncertainties and risks. You should carefully consider and evaluate all of the information included and incorporated by reference in this prospectus supplement and the accompanying prospectus, including the risk factors incorporated by reference from our most recent Annual Report on Form 10-K, as updated by other SEC filings filed after such report. Our business, financial condition, results of operations and prospects could be materially adversely affected by any of these risks. The occurrence of any of these risks may cause you to lose all or part of your investment.

Risks Related to Our Business

We may be classified as a passive foreign investment company in any taxable year and U.S. holders of our ADSs could be subject to adverse U.S. federal income tax consequences.

        The rules governing passive foreign investment companies, or PFICs, can have adverse effects for U.S. federal income tax purposes. The tests for determining PFIC status for a taxable year depend upon the relative values of certain categories of assets and the relative amounts of certain kinds of income. The determination of whether we are a PFIC depends on the particular facts and circumstances (such as the valuation of our assets, including goodwill and other intangible assets) and may also be affected by the application of the PFIC rules, which are subject to differing interpretations. Based on our estimated gross income, the average value of our assets, including goodwill, and the nature of our active business, we do not believe we were treated as a PFIC for U.S. federal income tax purposes for the U.S. taxable year ending December 31, 2016, however, no assurance can be given that the IRS or a court of law will accept this position, and there is a risk that the IRS or a court of law could determine that we are a PFIC. Moreover, our status for any taxable year will depend on our assets and activities in each year, and because this is a factual determination made annually after the end of each taxable year, there can be no assurance that we will not be considered a PFIC for this year or any future taxable year.

        If we are a PFIC, "U.S. Holders", as defined in "Taxation" below, of our ADSs would be subject to adverse U.S. federal income tax consequences, such as ineligibility for any preferred tax rates on capital gains or on actual or deemed dividends, interest charges on certain taxes treated as deferred, and additional reporting requirements under U.S. federal income tax laws and regulations. A U.S. Holder of our ADSs may be able to mitigate some of the adverse U.S. federal income tax consequences described above with respect to owning the ADSs if we are classified as a PFIC, provided that such U.S. Holder is eligible to make, and validly makes, a "mark-to-market" election. In certain circumstances a U.S. Holder can make a "qualified electing fund" election to mitigate some of the adverse tax consequences described with respect to an ownership interest in a PFIC by including in income its share of the PFIC's income on a current basis. However, we do not currently intend to prepare or provide the information that would enable a U.S. Holder to make a qualified electing fund election.

        Investors should consult their own tax advisors regarding all aspects of the application of the PFIC rules to our ADSs. For more information related to classification as a PFIC, see "Taxation—U.S. Federal Income Taxation—Passive Foreign Investment Company Considerations."

Risks Related to Our ADSs and this Offering

If you purchase ADSs in this offering, you will suffer immediate dilution of your investment.

        The offering price per ADS in this offering may exceed the net tangible book value per ADS outstanding prior to this offering. Therefore, if you purchase ADSs in this offering, you may pay a price per ADS that exceeds our as adjusted net tangible book value per ADS after this offering. To the

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extent outstanding options are exercised, you will incur further dilution. Assuming that an aggregate of            of our ADSs are sold at a price of $            per ADS pursuant to this prospectus supplement, for aggregate net proceeds of $            after deducting commissions and estimated aggregate offering expenses payable by us, you would experience immediate dilution of $            per ordinary share, or $            per ADS, representing the difference between our as adjusted net tangible book value per ordinary share as of December 31, 2016, after giving effect to this offering and the offering price. In addition, purchasers of ADSs in this offering will have contributed approximately        % of the aggregate price paid by all purchasers of our ordinary shares but will own only approximately        % of our ordinary shares outstanding after this offering, assuming that an aggregate of            of our ADSs are sold at a price of $            per ADS pursuant to this prospectus supplement, for aggregate gross proceeds of $            . See "Dilution."

We do not anticipate paying cash dividends, and accordingly, holders of our ADSs must rely on appreciation in the price of the ADSs for any return on their investment.

        We currently intend to retain our future earnings, if any, to fund the development and growth of our businesses. As a result, capital appreciation, if any, of our ADSs will be your sole source of gain on your investment for the foreseeable future. Investors seeking cash dividends should not invest in our ADSs.

If securities or industry analysts do not publish research or publish inaccurate or unfavorable research about our business, our ADS price and trading volume could decline.

        The trading market for our ADSs depends on the research and reports that securities or industry analysts publish about us or our business. We do not have any control over these analysts. We cannot assure you that analysts will cover us or provide favorable coverage. If one or more of the analysts who cover us downgrade our ADSs or change their opinion of our ADSs, our ADS price would likely decline. If one or more of these analysts cease coverage of our company or fail to regularly publish reports on us, we could lose visibility in the financial markets, which could cause our ADS price or trading volume to decline.

You may not have the same voting rights as the holders of our ordinary shares and may not receive voting materials in time to be able to exercise your right to vote.

        Except as described in this prospectus supplement and the accompanying prospectus, holders of the ADSs will not be able to exercise voting rights attaching to the ordinary shares represented by the ADSs on an individual basis. Holders of the ADSs will appoint the depositary or its nominee as their representative to exercise the voting rights attaching to the ordinary shares represented by the ADSs. You may not receive voting materials in time to instruct the depositary to vote, and it is possible that you, or persons who hold their ADSs through brokers, dealers or other third parties, will not have the opportunity to exercise a right to vote.

You may not receive distributions on our ordinary shares represented by the ADSs or any value for them if it is unlawful or impracticable to make them available to holders of ADSs.

        The depositary for the ADSs has agreed to pay to you the cash dividends or other distributions it or the custodian receives on our ordinary shares or other deposited securities after deducting its fees and expenses. You will receive these distributions in proportion to the number of our ordinary shares that your ADSs represent. However, in accordance with the limitations set forth in the deposit agreement, it may be unlawful or impracticable to make a distribution available to holders of ADSs. We have no obligation to take any other action to permit distribution on the ADSs, ordinary shares, rights or anything else to holders of the ADSs. This means that you may not receive the distributions we make on our ordinary shares or any value from them if it is unlawful or impracticable to make them available to you. These restrictions may have a material adverse effect on the value of your ADSs.

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USE OF PROCEEDS

        We estimate that we will receive total estimated net proceeds from this offering of approximately $             million, or $             million if the underwriters exercise their option to purchase additional ADSs in full, in each case after deducting estimated underwriting discounts and commissions and estimated expenses of the offering payable by us.

        We currently intend to use the net proceeds of this offering to advance our wholly-owned pipeline of SPEAR T-cell candidates through clinical trials as well as for other general corporate purposes. Although it is difficult to predict future capital requirements, we believe that the net proceeds from this offering, together with our existing cash resources and expected revenue contributions from our GSK collaboration and license agreement, will provide us with adequate cash resources to fund our operations through to the middle of 2019.

        Our expected use of net proceeds from this offering represents our current intentions based upon our present plans and business conditions. As of the date of this prospectus supplement, we cannot predict with certainty all of the particular uses for the net proceeds to be received upon the completion of this offering or the amounts that we will actually spend on the uses set forth above. The amounts and timing of our actual use of net proceeds will vary depending on numerous factors, including our ability to obtain additional financing, the relative success and cost of our research, preclinical and clinical development programs, including a change in our planned course of development or the termination of a clinical program necessitated by the results of data received from clinical trials or otherwise, the amount and timing of additional revenues, if any, received from our GSK collaboration and license agreement and whether we enter into future collaborations. As a result, management will have broad discretion in the application of the net proceeds, and investors will be relying on our judgment regarding the application of the net proceeds of this offering.

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DILUTION

        If you invest in our ADSs in this offering, your ownership interest will be diluted immediately to the extent of the difference between the price per ADS you pay in this offering and the net tangible book value per ADS after this offering.

        Our net tangible book value as of December 31, 2016 was $166.1 million, or $0.39 per ordinary share ($2.35 per ADS), based on 424,775,092 ordinary shares then outstanding. After giving effect to the assumed sale by us of                        ADSs at a public offering price of $            per ADS, less the estimated commissions and estimated offering expenses payable by us, our net tangible book value at December 31, 2016 would have been $             million, or $            per ordinary share. This represents an immediate increase in net tangible book value of $            per ordinary share ($            per ADS) to existing shareholders and an immediate dilution of $            per ordinary share ($            per ADS) to investors in this offering. The following table illustrates this per ADS dilution. The as adjusted information is illustrative only and will adjust based on the actual price to the public, the actual number of ADSs sold and other terms of the offering determined at the time our ADSs are sold pursuant to this prospectus supplement.

Public offering price per ADS

        $               

Net tangible book value per ADS as of December 31, 2016

  $ 2.35                   

Increase per ADS attributable to new investors purchasing ADSs in this offering

  $                     

As adjusted net tangible book value per ADS after giving effect to this offering

        $               

Dilution per ADS to new investors

        $               

        The above discussion and table are based on 424,775,092 ordinary shares outstanding as of December 31, 2016 and excludes 68,008,266 of our ordinary shares issuable upon the exercise of options outstanding as of March 20, 2017, at a weighted average exercise price of £0.59 per ordinary share.

        To the extent that outstanding options are exercised, you will experience further dilution. In addition, we may choose to raise additional capital due to market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans. To the extent that additional capital is raised through the sale of equity, the issuance of such securities may result in further dilution to our ADS holders.

        The share information above also:

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DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE

Directors

Name
  Age   Position

David M. Mott

    51   Chairman of the Board of Directors

Lawrence M. Alleva

    67   Non-Executive Director

Ali Behbahani, M.D. 

    40   Non-Executive Director

Barbara Duncan

    52   Non-Executive Director

Giles Kerr

    57   Non-Executive Director

Elliott Sigal, Ph.D, M.D. 

    65   Non-Executive Director

Peter Thompson, M.D. 

    57   Non-Executive Director

Tal Zaks, Ph.D, M.D. 

    51   Non-Executive Director

James Noble

    57   Chief Executive Officer and Director

        David M. Mott.    Mr. Mott has served as our Chairman since January 2017 and as a Non-Executive Director since September 2014, initially in a capacity as a nominee of New Enterprise Associates 14 LP (NEA), one of our shareholders. Mr. Mott has served as a General Partner of NEA, an investment firm focused on venture capital and growth equity investments, since 2008, and leads its healthcare investing practice. He was formerly President and Chief Executive Officer of MedImmune LLC, a subsidiary of AstraZeneca Plc, and Executive Vice President of AstraZeneca Plc. From 1992 to 2008, Mr. Mott worked at MedImmune and served in roles including Chief Operating Officer, Chief Financial Officer, President and Chief Executive Officer. Prior to joining MedImmune, Mr. Mott was a Vice President in the Health Care Investment Banking Group at Smith Barney, Harris Upham & Co., Inc. He is currently a member of the board of directors of Ardelyx, Epizyme and Tesaro, as well as several private companies, including 3-V Biosciences and Cydan, and has previously served on numerous public and private company boards in the biopharmaceutical industry, including Shire Pharmaceuticals, Ambit Pharmaceuticals, Onthera Pharmaceuticals, Prosensa Holding BV, Zyngenia and Conceptis. Mr. Mott received a bachelor of arts degree from Dartmouth College. Our Board of Directors believes Mr. Mott's qualifications to serve as a member of our board include his financial expertise, his experience as a venture capital investor, his extensive experience in the pharmaceutical industry and his years of experience in his leadership roles as a director and executive officer.

        Lawrence M. Alleva.    Mr. Alleva has served as a Non-Executive Director since March 2015. Mr. Alleva is a former partner with PricewaterhouseCoopers LLP (PwC), where he worked for 39 years from 1971 until his retirement in June 2010, including 28 years' service as a partner. Mr. Alleva worked with numerous pharmaceutical and biotechnology companies as clients and, additionally, served PwC in a variety of office, regional and national practice leadership roles, most recently as the U.S. Ethics and Compliance Leader for the firm's Assurance Practice from 2006 until 2010. Mr. Alleva currently serves as a director for public companies Tesaro Inc. (NASDAQ: TSRO), Bright Horizons Family Solutions Inc. (NYSE: BFAM) and Mirna Therapeutics Inc. (NYSE: MIRN), and chairs the audit committee for those companies. He previously served on the board of GlobalLogic, Inc. through the sale of the company in 2013 and also chaired the audit committee. Mr. Alleva is a Certified Public Accountant (inactive). He received a B.S. degree in Accounting from Ithaca College and attended Columbia University's Executive MBA non-degree program. Our Board of Directors believes Mr. Alleva's qualifications to serve as a member of our board include his financial expertise, his extensive experience working with public companies on corporate finance and accounting matters as a Certified Public Accountant (inactive), his experience serving as a director on other corporate boards and his experience in a senior leadership role at PwC.

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        Ali Behbahani, M.D.    Dr. Behbahani has served as a Non-Executive Director since September 2014, initially in a capacity as a nominee of NEA, one of our shareholders. Dr. Behbahani has been a Partner on the healthcare team at NEA since 2013, having worked for the fund since 2007, specializing in investments in the biopharmaceutical, medical device, specialty pharmaceutical and healthcare services sectors. He is also currently a member of the board of directors of Nevro Corp. and CRISPR Therapeutics AG. He also serves on the board of directors of several private companies, including Solace Therapeutics, Inc., ClarVista Medical, Inc. and NKarta, Inc. He has previously worked as a consultant in business development at The Medicines Company and held positions as a Venture Associate at Morgan Stanley Venture Partners from 2000 to 2002 and as a Healthcare Investment Banking Analyst at Lehman Brothers from 1998 to 2000. Dr. Behbahani conducted basic science research in the fields of viral fusion inhibition and structural proteomics at the National Institutes of Health and at Duke University. He holds an M.D. degree from The University of Pennsylvania School of Medicine and an MBA from the Wharton School of the University of Pennsylvania. Our Board of Directors believes Dr. Behbahani's qualifications to serve as a member of our board include his financial expertise, his experience as a venture capital investor, his extensive experience in the healthcare industry and his years of experience in his leadership roles as a director and executive officer.

        Barbara Duncan.    Ms. Duncan has served as a Non-Executive Director since June 2016. She has over 15 years of experience in the life sciences industry and served as Chief Financial Officer and Treasurer at Intercept Pharmaceuticals, Inc. (NASDAQ: ICPT) from May 2009 to 2016 and as Chief Financial Officer and then Chief Executive Officer at DOV Pharmaceuticals, Inc. from 2001 to 2009. Prior to joining DOV, Ms. Duncan served as Vice President of Corporate Finance—Global Healthcare at Lehman Brothers Inc. from 1998 to 2001, and as Director of Corporate Finance at SBC Warburg Dillon Read Inc. from 1994 to 1998. She also worked for PepsiCo, Inc. from 1989 to 1992 in its international audit division, and was a certified public accountant in the audit division of Deloitte & Touche LLP from 1986 to 1989. Ms. Duncan currently serves as a director for public companies Aevi Genomic Medicine (NASDAQ: GNMX), Jounce Therapeutics, Inc. (NASDAQ: JNCE) and Innoviva, Inc. (NASDAQ: INVA), and for privately-held companies, Edgemont Pharmaceuticals, LLC and Observa, Inc. She holds an MBA from the Wharton School of the University of Pennsylvania and a Bachelor of Business Administration from Louisiana State University. Our Board of Directors believes Ms. Duncan's qualifications to serve as a member of our board include her financial expertise, her extensive experience in the healthcare industry and her years of experience in her leadership roles as a director and executive officer.

        Giles Kerr.    Mr. Kerr has served as a Non-Executive Director since November 2016. He has substantial commercial and financial experience gained from service on numerous public and private company boards and as an audit partner. Mr. Kerr has served as Director of Finance of the University of Oxford since 2005. He also currently serves as a Board member and Audit Committee member of public companies BTG plc (LSE: BTG), Paypoint plc (LSE: PAY) and Senior plc (LSE: SNR) as well as on the boards of several private companies, including Quanta Dialysis Technologies Ltd, Oxford Sciences Innovation plc and Oxford Capital Fund. Mr. Kerr previously served in roles of increasing seniority at Amersham plc since 1990, including as Chief Financial Officer and a Board member from 1997 to 2004, when the company was acquired by GE Healthcare, and as a director of Victrex plc and of Elan Corporation Inc. Prior to his role at Amersham, Mr. Kerr was a National Partner with Arthur Andersen. He is a Fellow of the Institute of Chartered Accountants of England and Wales and holds a B.A. degree in Economics from the University of York, U.K. Our Board of Directors believes Dr. Kerr's qualifications to serve as a member of our board include his financial expertise, his extensive experience in the healthcare industry and his years of experience in his leadership roles as a director and executive officer.

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        Elliott Sigal, M.D., Ph.D.    Dr. Sigal has served as a Non-Executive Director since September 2014 and is a former Executive Vice President and member of the Board of Directors of Bristol-Myers Squibb. He joined BMS in 1997 as head of Applied Genomics, went on to head Discovery Research followed by clinical development and ultimately served as Chief Scientific Officer and President of R&D from 2004 until 2013. Dr. Sigal serves as a board member for the Mead Johnson Nutrition Company, Spark Therapeutics and the Melanoma Research Alliance. He also serves as a senior advisor to the healthcare team of NEA and consults for several biotechnology companies. Dr. Sigal holds an M.D. from the University of Chicago and trained in Internal Medicine and Pulmonary Medicine at the University of California, San Francisco, where he was on faculty from 1988 to 1992. He also holds a B.S., M.S, and Ph.D. in engineering from Purdue University. Our Board of Directors believes Dr. Sigal's qualifications to serve as a member of our board include his extensive experience in the pharmaceutical industry and his years of experience in his leadership roles as a director and executive officer.

        Peter Thompson, M.D.    Dr. Thompson has served as a Non-Executive Director since September 2014, initially in his capacity as a nominee of OrbiMed Private Investments V, L.P. (OrbiMed), one of our shareholders. Dr. Thompson is currently a Private Equity Partner with OrbiMed who brings over 25 years of industry experience. He co-founded and was Chief Executive Officer of Trubion Pharmaceuticals from 2002 to 2009 (NASDAQ: TRBN), co-founded Cleave BioSciences and Corvus Pharmaceuticals (NASDAQ:CRVS), and was previously an executive of Chiron Corporation and Becton Dickinson. Dr. Thompson also serves as a Director on several public and private company Boards including Cardioxyl Pharmaceuticals, Inc., Cleave Biosciences, PMV Pharmaceuticals, Inc., Principia BioPharma, ProNai Therapeutics, Inc., Response BioMedical Corp, and OxOnc Development Inc. He is also an Ernst & Young Entrepreneur of the Year awardee and an Affiliate Professor of Neurosurgery at the University of Washington. He is the inventor on numerous patents, is a board-certified internist and oncologist and was on the staff at the National Cancer Institute following his internal medicine training at Yale University. Our Board of Directors believes Dr. Thompson's qualifications to serve as a member of our board include his financial expertise, his experience as a venture capital investor, his extensive experience in the pharmaceutical industry and his years of experience in his leadership roles as a director and executive officer.

        Tal Zaks, Ph.D, M.D.    Dr. Zaks has served as a Non-Executive Director since November 2016. He has substantial research, development and commercialization experience gained from service in industry and academia. Dr. Zaks has served as the Chief Medical Officer of Moderna Therapeutics, Inc. since March 2015. He previously served as Senior Vice President and Head of Global Oncology at Sanofi Inc, where he was responsible for all aspects of oncology drug discovery, development and commercialization. Dr. Zaks began his industry career at GlaxoSmithKline in the genetics research group, where he built the oncology translational medicine team and led translational research on lapatinib as well as the in-licensing and clinical development of foretinib. In addition to his industry work, Dr. Zaks is an Adjunct Associate Professor of Medicine at the University of Pennsylvania and has served as a volunteer physician at the Philadelphia Veterans Administration Medical Center, treating patients with genitourinary cancers. Dr. Zaks received his M.D. and Ph.D. degrees from the Ben Gurion University in Israel and conducted post-doctoral research at the U.S. National Institutes of Health. He completed his clinical training in internal medicine at Temple University Hospital followed by a fellowship in medical oncology at the University of Pennsylvania. Our Board of Directors believes Dr. Zaks' qualifications to serve as a member of our board include his extensive experience in the biopharmaceutical industry and his years of experience in his leadership roles as an executive officer.

        James Noble.    Mr. Noble has served as our full-time Chief Executive Officer since March 2014 and part-time CEO from July 2008 to March 2014 and is one of our co-founders. From July 2008 until March 2014, Mr. Noble was also part-time CEO of Immunocore Limited. Mr. Noble has 24 years of experience in the biotech industry. He has held numerous non-executive director positions including at

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CuraGen Corporation, PowderJect Pharmaceuticals plc, Oxford GlycoSciences plc, MediGene AG, and Advanced Medical Solutions plc. Mr. Noble is also Deputy Chairman of GW Pharmaceuticals plc (NASDAQ: GWPH). Mr. Noble qualified as a chartered accountant with PwC and spent seven years at the investment bank Kleinwort Benson Limited, where he became a director in 1990. He then joined British Biotech plc as Chief Financial Officer from 1990 to 1997. Mr. Noble was previously Chief Executive Officer of Avidex Limited, a privately held biotechnology company that was our predecessor, from 2000 to 2006. Mr. Noble holds an MA from the University of Oxford. Our Board of Directors believes Mr. Noble's qualifications to serve as a member of our board include his financial expertise, his extensive experience in the biopharmaceutical industry and his years of experience in his leadership roles as a director and executive officer.

Executive Officers

Name
  Age   Position

James Noble

    57   Chief Executive Officer and Director

William Bertrand

    52   Chief Operating Officer

Helen Tayton-Martin, Ph.D

    50   Chief Business Officer

Rafael Amado, M.D. 

    53   Chief Medical Officer

Adrian Rawcliffe

    44   Chief Financial Officer

Gwendolyn Binder-Scholl, Ph.D

    42   Chief Technology Officer, Adaptimmune LLC

        William Bertrand.    Mr. Bertrand has served as our Chief Operating Officer since March 2017 and is responsible for a range of operational functions including compliance, risk management, human resources and legal/IP. Mr. Bertrand's prior experience includes a 12 year tenure at MedImmune, where he served as its first General Counsel and Chief Compliance Officer, along with holding a variety of operational and corporate strategy roles. He has also formerly served as Executive Vice President, General Counsel for Infinity Pharmaceuticals, Inc., and as Senior Vice President, Acting Chief Operating Officer and General Counsel for Salix Pharmaceuticals, where he remained as General Manager to help finalize the integration of the company's $14 billion acquisition by Valeant Pharmaceuticals in April 2015. He is currently a member of the board of directors of Ardelyx, Inc. (NASDAQ: ARDX) and has served as a member of the board of directors of several private companies including Trustwave Holdings and Inotek Pharmaceuticals. Mr. Bertrand received a J.D. from the University of Wisconsin and a B.S. in biology from Wayne State University.

        Helen Tayton-Martin, Ph.D.    Dr. Tayton-Martin transitioned to become Adaptimmune's Chief Business Officer in March 2017, having served as Chief Operating Officer since 2008. She is responsible for optimizing the strategic and commercial opportunity for the Company's assets, leading on business development and commercial activities. Her role encompasses all aspects of pipeline and technology assessment, strategic portfolio analysis, integrated program management, commercial planning and partnerships, including our strategic partnership with GSK. Dr. Tayton-Martin has 25 years of experience working within the pharmaceutical, biotech and consulting environment in disciplines across preclinical and clinical development, outsourcing, strategic planning, due diligence and business development. She co-founded Adaptimmune from Avidex Limited (subsequently Medigene), where she was responsible for commercial development of the soluble TCR program in cancer and HIV therapy from 2005 to 2008. Dr. Tayton-Martin holds a Ph.D. in molecular immunology from the University of Bristol, U.K. and an M.B.A. from London Business School.

        Rafael Amado, M.D.    Dr. Amado has served as our Chief Medical Officer since March 2015 and has 12 years of experience within the biotech and pharmaceutical industries. Dr. Amado leads our clinical strategy and is responsible for our clinical trials across the U.S. and Europe under our strategic collaboration with GSK (LSE/NYSE: GSK), as well as leading the development of our pipeline of wholly-owned research programs. He formerly served as Senior Vice President and Head of Oncology

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R&D at GSK, where he was responsible for integrating oncology R&D activities, from drug target identification to clinical development and registration globally. Dr. Amado joined GSK in 2008 as Vice President of Clinical Development, and served in positions of increasing responsibility, including Senior Vice President and Head of Oncology Clinical Development. He oversaw the development and registration globally of over fifteen novel indications across six products and led the development of a pipeline of products in novel areas of cancer biology. Prior to joining GSK, Dr. Amado was Executive Director of Therapeutic Oncology at Amgen from 2003 to 2008 where he was responsible for development activities of several assets. Dr. Amado trained as a Hematologist/Oncologist at the University of California, Los Angeles, where he remained as faculty for eight years until joining Amgen in 2003. He holds an M.D. from the University of Seville School of Medicine, and performed his residency in Internal Medicine at Michael Reese Hospital, a University of Chicago Affiliated Hospital, and his fellowship in Hematology/Oncology at the University of California, Los Angeles.

        Adrian Rawcliffe.    Mr. Rawcliffe has served as our Chief Financial Officer since March 2015 and leads our financial strategy and operations, as well as Investor Relations, corporate communications, global IT and facilities. He has 17 years of experience within the pharmaceutical industry and most recently served as Senior Vice President, Finance of GSK's North American Pharmaceuticals business. Mr. Rawcliffe currently serves as a non-executive director of WAVE Life Sciences (NASDAQ: WVE). Mr. Rawcliffe joined GSK in 1998 and his other senior roles at the company included Senior Vice President Worldwide Business Development and R&D Finance, where he was responsible for all business development and finance activities for GSK's Pharmaceuticals R&D business and Managing Partner and President of SR One Ltd, GSK's venture-capital business. Mr. Rawcliffe qualified as a chartered accountant with PwC and holds a B.Sc. degree in Natural Sciences from the University of Durham, U.K..

        Gwendolyn Binder-Scholl, Ph.D.    Dr. Binder-Scholl has served as our Chief Technology Officer since February 2016. Prior to assuming this position, Dr. Binder-Scholl was Executive Vice President of Adaptimmune LLC and Head of Translational Sciences. She has also previously served in senior clinical, regulatory and operational roles in the company since March 2011. As CTO, Dr. Binder-Scholl leads our Manufacturing Development and Translational Science operations and oversees the UK research team. Her strategic focus is on optimizing the therapeutic potential of Adaptimmune's product through directed translational research across correlative clinical and manufacturing development. As well as her leadership of manufacturing operations, she oversees process development and the co-ordination of Research operations more broadly, integrating pipeline and second generation T-cell research with clinical outcomes. Dr. Binder-Scholl has 14 years of industry and academic experience in cellular and gene therapy translational research and development, with prior roles including Director of Translational Research Operations at the University of Pennsylvania from 2006 to 2011 and Director of Scientific Affairs at Virxsys Corporation. Dr. Binder-Scholl is a biochemistry and molecular biology graduate of Wells College with a Ph.D. in cellular and molecular medicine from Johns Hopkins University.

Code of Business Conduct and Ethics

        We have adopted a Code of Business Conduct and Ethics applicable to all of our employees, officers and directors. The Code of Business Conduct and Ethics is available on our website. Any amendment to this code, or any waivers of its requirements, will be disclosed on our website.

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Committees of our Board of Directors

        Our Board of Directors has three standing committees: the Audit Committee; the Remuneration Committee; and the Corporate Governance and Nominating Committee. The charters for each of these committees can be found on our website.

Name
  Audit   Remuneration   Corporate Governance
and Nominating

David M. Mott

      Chair   Chair

Lawrence M. Alleva

  Chair        

Ali Behbahani, M.D. 

          X

Barbara Duncan

  X        

Giles Kerr

  X       X

Elliott Sigal, Ph.D, M.D. 

          X

Peter Thompson, M.D. 

      X    

Tal Zaks, Ph.D, M.D. 

      X    

Audit Committee

        Our Audit Committee is currently composed of Mr. Alleva, Ms. Duncan and Mr. Kerr, with Mr. Alleva serving as chairman of the committee. Our Board of Directors has determined that each member of the Audit Committee meets the independence requirements of Rule 10A-3 under the Exchange Act and the applicable listing standards of The NASDAQ Global Market. Our Board of Directors has determined that each of Mr. Alleva, Ms. Duncan and Mr. Kerr is an "audit committee financial expert" within the meaning of SEC regulations and the applicable listing standards of The NASDAQ Global Market. The Audit Committee held eight meetings during 2016. The Audit Committee's responsibilities include:

Remuneration Committee

        Our Remuneration Committee is currently composed of Mr. Mott, Dr. Thompson and Dr. Zaks, with Mr. Mott serving as chairman of the committee. Our Board of Directors has determined that each member of the Remuneration Committee is "independent" as defined under the applicable listing standards of The NASDAQ Global Market. The Remuneration Committee held five meetings during 2016. The Remuneration Committee's responsibilities include:

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        No individual will participate in discussion or decisions concerning his or her own remuneration. None of the members of our Remuneration Committee has at any time during the prior three years been one of our officers or employees. None of our executive officers currently serves, or in the past fiscal year has served, as a member of our Remuneration Committee or the remuneration committee of any entity that has one or more executive officers serving on our Board of Directors.

Corporate Governance and Nominating Committee

        Our Corporate Governance and Nominating Committee is composed of Mr. Mott, Dr. Behbahani, Mr. Kerr and Dr. Sigal, with Mr. Mott serving as chairman of the committee. Our Board of Directors has determined that each member of the Corporate Governance and Nominating Committee is "independent" as defined under the applicable listing standards of The NASDAQ Global Market. The Corporate Governance and Nominating Committee held four meetings during 2016. The Nominating and Corporate Governance Committee's responsibilities include:

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Independence of our Board of Directors

        Our Board of Directors has determined that all of our directors, other than Mr. Noble, qualify as "independent" directors in accordance with the independence requirements under the applicable listing standards of The NASDAQ Global Market as well as applicable rules promulgated by the SEC. Mr. Noble is not considered independent because he is an employee of the Company.

        Our Board of Directors has made a subjective determination as to each independent director that no relationships exist that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director. In making these determinations, our Board of Directors reviewed and discussed information provided by the directors and us with regard to each director's business and personal activities and relationships as they may relate to us and our management. There are no family relationships among any of our directors or executive officers.

        Our independent directors meet in regularly scheduled executive sessions at which only independent directors are present. All of the committees of our Board of Directors are comprised entirely of directors determined by the Board of Directors to be independent.

Board Oversight of Risk Management

        Our management is primarily responsible for assessing and managing risk, while our Board of Directors is responsible for overseeing management's execution of its responsibilities. Our Board of Directors is supported by its committees in fulfillment of this responsibility. For example, our Audit Committee focuses on our overall financial risk by evaluating our internal controls and disclosure policies as well as ensuring the integrity of our financial statements and periodic reports. Our Remuneration Committee strives to create incentives that encourage an appropriate level of risk-taking consistent with our business strategy. Finally, our Corporate Governance and Nominating Committee ensures that our governance policies and procedures are appropriate in light of the risks we face. Our Chief Executive Officer, Mr. Noble, serves on our Board of Directors; however, he does not serve as Chairman of the Board of Directors. Mr. Mott serves as Chairman of the Board of Directors.

Director Nomination Process

        The Corporate Governance and Nominating Committee of the Board of Directors reviews possible candidates for the Board and recommends the nominees for Directors to the Board for approval. The criteria that the Corporate Governance and Nominating Committee and the Board of Directors look for in determining candidates for election to the Board, include, among others:

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        It is the Corporate Governance and Nominating Committee's policy that the composition of the Board of Directors reflect a range of talents, ages, skills, character, diversity and expertise, particularly in the areas of accounting and finance, management, domestic and international markets, leadership, corporate governance, and biotechnology and related industries, sufficient to provide sound and prudent guidance with respect to the operations and interests of the Company.

        The Corporate Governance and Nominating Committee's policy does not contemplate any disparate treatment of management nominees versus those put forth by our shareholders. To date, the Committee has worked with Egon Zehnder, an independent global board and executive search firm, to assist in identifying and evaluating potential nominees against role specifications.

Shareholder Recommendations and Nominees

        It is the policy of our Board of Directors that the Nominating and Corporate Governance Committee consider both recommendations and nominations for candidates to the Board from shareholders so long as such recommendations and nominations comply with our Articles of Association and applicable laws, including the rules and regulations of the SEC. Shareholders may recommend director nominees for consideration by the Corporate Governance and Nominating Committee by writing to our Company Secretary at the Company's registered office address and providing evidence of the shareholder's ownership of our ordinary shares and/or ADSs, the nominee's name, home and business address and other contact information, as well as the nominee's detailed biographical data and qualifications for board membership, and information regarding any relationships between the recommended candidate and the Company within the last three fiscal years.

        Following verification of the shareholder status of the person submitting the recommendation, all properly submitted recommendations will be promptly brought to the attention of the Corporate Governance and Nominating Committee. Shareholders who desire to nominate persons directly for election to the Board at an annual general meeting of shareholders must meet the deadlines and other requirements for shareholder proposals at our annual general meeting. Any vacancies on the Board of Directors occurring between our annual general meetings of shareholders may be filled by persons selected by a majority of the directors then in office, and any director so elected will serve until the next shareholders' meeting at which directors are elected when such director will offer himself/herself for re-election.

Shareholder Communication with the Board of Directors

        It is the policy of our Board of Directors to allow shareholders to communicate with its members. Communications may be addressed to the entire board or to any individual director. All such communications will initially be received and processed by our Company Secretary. Spam, junk mail, advertisements and threatening, hostile, illegal and similar unsuitable communications will not be delivered to the Board. Shareholders can contact members of the Board of Directors, by writing care of our Company Secretary at the Company's registered office address.

Section 16(A) Beneficial Ownership Reporting Compliance

        All of our directors, executive officers and any greater than 10 percent shareholders are required by Section 16(a) of the Exchange Act to file with the SEC initial reports of ownership and reports of changes in ownership of shares and to furnish us with copies of such reports. Based on a review of those reports and written representations that no other reports were required, we believe that our Section 16 directors and executive officers complied with all of their applicable Section 16(a) filing requirements.

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Executive and Director Compensation

Executive Compensation

        This section discusses the material components of the executive compensation program offered to our named executive officers, or NEOs, identified below. For the year ended December 31, 2016, these NEOs were:

        We are an "emerging growth company" as that term is used in the Jumpstart Our Business Startups Act of 2012, or JOBS Act, and have elected to comply with the reduced compensation disclosure requirements available to emerging growth companies under the JOBS Act.

2016 Summary Compensation Table

Name and Principal Position
  Year   Salary
($)
  Option
awards
($)(4)
  Non-equity
incentive plan
compensation
($)(5)
  All other
compensation
($)
  Total
($)
 

James Noble(1)

    2016     388,395 (3)   1,411,405     97,099     20,465     1,917,364  

Chief Executive Officer

    2015     442,080 (3)       294,720     24,621     761,421  

Adrian Rawcliffe

    2016     435,000     674,104     117,450     34,262.14 (6)   1,260,816.14  

Chief Financial Officer(2)

    2015     336,452     2,379,693     151,403     42,386.94 (7)   2,909,934.94  

Rafael Amado

    2016     430,000     674,104     116,100     20,289.90 (8)   1,240,493.9  

Chief Medical Officer(2)

    2015     331,358     2,379,693     149,111     31,948.66 (9)   2,892,110.66  

(1)
Mr. Noble also serves as a director but receives no additional compensation for this service.

(2)
Mr. Rawcliffe and Dr. Amado commenced employment with us on March 16, 2015. The 2015 salary shown for Mr. Rawcliffe represents the pro-rated amount of his base salary of $425,000 and the 2015 salary shown from Dr. Amado represents the pro-rated amount of his base salary of $418,200. The 2015 non-equity incentive plan compensation amounts shown for Mr. Rawcliffe and Dr. Amado are based on 45% of their pro-rated 2015 base salaries.

(3)
Compensation paid to Mr. Noble is denominated in Pounds Sterling. For purposes of this table, all 2016 amounts have been converted based on the Pound Sterling/U.S. Dollar exchange rate in effect as of December 31, 2016 (£1/$1.233) and all 2015 amounts have been converted based on the Pound Sterling/U.S. Dollar exchange rate in effect as of December 31, 2015 (£1/$1.4736).

(4)
See Item 7—"Share based compensation" and in Note 2 (r) and Note 10 "Share based compensation" to our audited consolidated financial statements, in our Form 10-K for an explanation of the assumptions used in the calculation of these amounts.

(5)
Amount represents sums paid under our annual cash bonus program.

(6)
Consists of Company payments in the amount of (i) $16,962.14 to subsidize city of Philadelphia taxes, (ii) $5,300 in matching contributions under the 401(k) plan and (iii) $12,000 to private health care insurance on behalf of Mr. Rawcliffe.

(7)
Consists of Company payments in the amount of (i) $13,188.94 to subsidize city of Philadelphia taxes, (ii) $20,198 in matching contributions under the 401(k) plan and (iii) $9,000 to private health care insurance on behalf of Mr. Rawcliffe.

(8)
Consists of Company payments in the amount of (i) $14,989.90 to subsidize city of Philadelphia taxes and $5,300 in matching contributions under the 401(k) plan.

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(9)
Consists of Company payments in the amount of (i) $11,750.66 to subsidize city of Philadelphia taxes and (ii) $20,198 in matching contributions under the 401(k) plan.

Narrative Disclosure to Summary Compensation Table

        The primary elements of compensation for our NEOs are base salary, annual cash bonuses and long-term, equity-based compensation awards. Our NEOs also participate in employee benefit plans and programs that we offer to our other full-time employees on the same basis and have from time to time received relocation or other expense reimbursements from us.

        Base Salary.    Our NEOs receive base salary to compensate them for the satisfactory performance of duties to our company. The base salary payable to each NEO is intended to provide a fixed component of compensation reflecting the executive's skill set, experience, role and responsibilities.

        Our Remuneration Committee periodically reviews NEO base salaries in consultation with management and Willis Towers Watson, an independent compensation consultant, to determine whether any adjustments are necessary or appropriate. The following table shows the annual base salaries of our NEOs for 2016 and 2017. All annual base salary increases were effective January 1 of the given year.

Name
  2016
Annual Base
Salary ($)
  2017
Annual Base
Salary ($)
 

James Noble(1)

    388,395     502,854  

Adrian Rawcliffe

    435,000     443,700  

Rafael Amado

    430,000     442,900  

(1)
Compensation paid to Mr. Noble is denominated in pounds sterling. For purposes of this table, 2016 and 2017 amounts for Mr. Noble in the table above have been converted based on the pound sterling/U.S. dollar exchange rate in effect as of December 31, 2016 (£1/$1.233).

        Annual Cash Bonuses.    Our NEOs have the opportunity to earn annual performance bonuses based on the achievement of short-term performance goals, and which are expressed as a percentage of base salary.

        Our Remuneration Committee generally determines annual bonuses for our NEOs, and the Board determines the annual bonus for our CEO, subject to: (i) objective criteria set forth by the Board of Directors or an authorized delegate thereof on an annual basis; and (ii) the overall performance of the Company and the Group. The initial target annual bonus with effect from January 1, 2017 for Mr. Noble is fifty percent (50%) of his base salary and for each of Mr. Rawcliffe and Dr. Amado is forty-five percent (45%) of his base salary.

        Equity-Based Compensation.    We have historically offered share options to our employees, including our NEOs, as the long-term incentive component of our compensation program. We typically grant options to employees as soon as practicable after they commence employment with us and may thereafter grant additional options in the discretion of our Board of Directors or Remuneration Committee. Our share options allow employees to purchase our ordinary shares at a price equal to the fair market value of our ordinary shares on the date prior to the grant date. Our share options typically vest as to 25% of the shares subject to the option on the first anniversary of the grant date and in monthly installments during the three-year period thereafter, subject to the holder's continued service with us. From time to time, our Board of Directors or Remuneration Committee may also construct alternate vesting schedules as it determines in its sole discretion.

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        We awarded share options to our NEOs during 2016 in the following amounts and subject to vesting in accordance with our standard time-based vesting schedule described above:

Named Executive Officer
  2016 Options
Granted (#)
 

James Noble

    1,968,016  

Adrian Rawcliffe

    939,948  

Rafael Amado

    939,948  

        Retirement, Health, Welfare and Additional Benefits.    Our NEOs are eligible to participate in our employee benefit plans and programs, including medical and dental benefits and life insurance, to the same extent as our other full-time employees, subject to the terms and eligibility requirements of those plans. We also sponsor a 401(k) defined contribution plan in which our NEOs based in the United States may participate, subject to limits imposed by the Internal Revenue Code, to the same extent as all of our other full-time employees. During 2016, we made discretionary employer matching contributions equal to 50% of the first 4% of the elective contributions made by participants in the 401(k) plan. These matching contributions are subject to a vesting schedule. In addition, we made a 3% discretionary Safe Harbor match which is fully vested as of the date on which the contribution is made. We believe that providing a vehicle for tax-deferred retirement savings through our 401(k) plan adds to the overall desirability of our executive compensation package and further incentivizes our employees, including our NEOs, in accordance with our compensation policies. We do not typically provide any perquisites or special personal benefits to our NEOs, but have from time to time reimbursed amounts associated with relocation and other expenses for our NEOs.

Outstanding Equity Awards at 2016 Fiscal Year-End

        The following table sets forth information regarding equity awards held by our named executive officers as of December 31, 2016. All options are options to purchase ordinary shares.

Name
  First date some
or all options
are exercisable
  Number of
securities
underlying
unexercised
options (#)
exercisable
  Number of
securities
underlying
unexercised
options(#)
unexercisable(1)
  Option
exercise
Price ($)(2)
  Option
expiration
date
 

James Noble

    3/31/2014 (3)   1,055,000     280,000     0.1671     03/30/2024  

    3/31/2015 (4)   219,000     219,000     0.1671     03/30/2024  

    12/19/2015 (5)   1,749,800     1,750,200     0.5308     12/19/2024  

    01/18/2017 (6)   0     1,968,016     1.2717     01/18/2026  

Adrian Rawcliffe

    03/16/2016 (7)   1,575,000     2,025,000     0.74     03/16/2025  

    01/18/2017 (8)   0     939,948     1.2717     01/18/2026  

Rafael Amado

    03/16/2016 (7)   1,575,000     2,025,000     0.74     03/16/2025  

    01/18/2017 (8)   0     939,948     1.2717     01/18/2026  

(1)
Vesting of all options is subject to continued service through the applicable vesting date.

(2)
The exercise price was converted from pounds sterling to U.S. dollars based on the noon buying rate of the Federal Reserve Bank of New York for the U.S. dollar on the date of grant. The actual exercise price will be the pounds sterling amount regardless of the exchange rate on the date of grant or of exercise.

(3)
This option was partially vested and the remainder will vest in annual installments on the thirty first of March from March 31, 2017 through March 31, 2018.

(4)
This option was partially vested and 109,500 ordinary shares will vest on April 14, 2017 and 190,600 ordinary shares will vest on April 14, 2018.

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(5)
This option was partially vested and the remainder will vest in monthly installments of 72,900 ordinary shares on the nineteenth of each month from March 19, 2017 through November 19, 2018, and in one installment of 73,500 ordinary shares on December 19, 2018.

(6)
This option partially vests as to 492,004 ordinary shares on January 18, 2017 and the remainder will vest in monthly installments of 41,000 ordinary shares on the eighteenth of each month from February 18, 2017 through December 18, 2019, and in one installment of 41,012 ordinary shares on January 18, 2020.

(7)
This option was partially vested and the remainder will vest in monthly installments of 75,000 ordinary shares on the sixteenth of each month from April 16, 2016 through March 16, 2019.

(8)
This option partially vests as to 234,987 ordinary shares on January 18, 2017, and the remainder will vest in monthly installments of 19,582 ordinary shares on the eighteenth of each month from February 18, 2017 through December 18, 2019, and in one installment of 19,591 ordinary shares on January 18, 2020.

Employment Agreements

        We have entered into a service agreement with our Chief Executive Officer and employment agreements with each of our NEOs. Certain key terms of those agreements and our executive severance policy are described below.

        We entered into a service agreement with Mr. Noble dated March 10, 2017 that sets forth the terms and conditions under which Mr. Noble serves as our Chief Executive Officer and as a director. The employment shall continue until terminated by either party giving no less than nine months' written notice. Mr. Noble's current annual base salary, effective January 1, 2017, is £407,830, subject to review, and Mr. Noble is eligible for an annual bonus at the discretion of the Company subject to the achievement of certain performance criteria.

        In addition, we may terminate the agreement immediately by notice if Mr. Noble (i) commits a material breach under the agreement, (ii) is guilty of conduct tending to bring him or the company into disrepute, (iii) becomes bankrupt, (iv) fails to perform his duties to a satisfactory standard, (v) is disqualified from being a director by reason of any order made under the Companies Directors Disqualification Act 1986 or any other enactment, or (vi) is convicted of an offence under any statutory enactment or regulation (including the criminal offence of insider dealing under the Criminal Justice Act 1993 or any similar conviction in the United States, but excluding a motoring offence for which no custodial sentence is given).

        Mr. Noble is eligible to participate in the Company's share option schemes, Group Personal Pension Scheme and in the private health care scheme and permanent health insurance schemes which the Company or any Group Company may maintain for the benefit of its senior executives.

        Mr. Noble's service agreement contains non-solicitation and non-competition provisions for a twelve month period as well as confidentiality provisions.

        The employment agreements for Mr. Rawcliffe and Dr. Amado were entered into on March 10, 2017. The agreements have no specific term and establish an at-will employment relationship. Mr. Rawcliffe's current annual base salary, effective January 1, 2017, is $443,700 and Dr. Amado's current annual base salary is $442,900, subject to periodic review and adjustment by the Company, and their annual target bonus opportunities are 45% of their annual base salaries subject to the achievement of certain performance criteria.

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        Mr. Rawcliffe and Dr. Amado are eligible to participate in the equity plans sponsored and/or maintained by the Company and its affiliates from time to time, in accordance with the terms of any such plans, at the sole and absolute discretion of the Company and the Board of Directors.

        The Company may terminate either of their employment with or without cause and without notice, but Mr. Rawcliffe and Dr. Amado are required to provide at least 60 days' advance written notice to us if he is terminating his employment. In the event of a termination of his employment by the Company without Cause or by Mr. Rawcliffe or Dr. Amado for good reason, any portion of his initial award of 3,500,000 share options that was granted on March 16, 2015, which is unvested as of the date of termination shall vest and immediately become exercisable on the date of termination. The agreements contain non-solicitation and non-competition provisions for a twelve month period as well as confidentiality provisions.

        The Company's executive severance policy is applicable in relation to our NEOs. If the employment of any of our NEOs is terminated by the Company without cause, or if he resigns for good reason, then the NEO will be entitled under his employment agreement and the executive severance policy to receive a severance payment equal to his annual base salary for nine months and to payment of premiums for continuation of healthcare benefits for a period of nine months following such termination. In addition, at the sole discretion of the Board (or an authorized committee thereof), the NEO may be paid a lump sum cash amount equal to his target annual performance bonus for the year of termination, prorated based on the number of calendar days he was employed during the year. Furthermore, if the employment of any of our NEOs is terminated without cause or he resigns for good reason within 12 months following a change in control, he will be entitled to receive a severance payment equal to his annual base salary for 12 months, payment of premiums for continuation of healthcare benefits for a period of 12 months, a lump sum cash amount equal to the full target performance bonus for the year of termination, and accelerated vesting of any unvested and outstanding equity awards. In order to receive severance benefits under the employment agreement and executive severance policy, the NEO is required to execute a release of claims in favor of the Company and comply with certain other post-employment covenants set forth in his employment agreement.

Retirement Plans

        We maintain a tax-qualified retirement plan for our U.S.-based employees that provides eligible employees with an opportunity to save for retirement on a tax-advantaged basis. We make discretionary employer matching contributions equal to 50% of the first 4% of the elective contributions made by participants in the 401(k) plan. These company matching contributions are subject to a vesting schedule. In addition, we make a 3% discretionary Safe Harbor matching contribution, which is fully vested as of the date of the contribution. Pre-tax contributions are allocated to each participant's individual account and are then invested in selected investment alternatives according to the participant's directions. The 401(k) plan is intended to qualify under Sections 401(a) and 501(a) of the Internal Revenue Code. As a tax-qualified retirement plan, contributions to the 401(k) plan and earnings on those contributions are not taxable to the employees until distributed from the 401(k) plan.

        In the U.K., we maintain a defined contribution plan that provides employees with an opportunity to contribute a portion of their monthly salary into the plan. If an employee elects to participate in the plan, there is a minimum employee contribution of 5% of monthly salary; there is no maximum limit to the employee contribution. The employee contribution to this plan is matched by us up to a maximum of 5% of monthly salary. All U.K. employees are eligible to participate in this plan. The method by which our U.K. employees participate is through a so-called "salary exchange" pursuant to which employees agree to a reduction in monthly salary in an amount equal to the defined contribution plan election. The amount of the reduction, together with the tax and national insurance savings to the employee and us as a result of the salary reduction, are contributed into the plan in addition to the 5% matching contribution described above.

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Director Compensation

        The Board has the discretion to pay our Non-Executive Directors for their Board and committee service in the form of cash fees or share options or a mixture of cash fees and share options. Our remuneration arrangements for Non-Executive Directors during 2016 comprised an award of a fixed number of share options, plus an additional number of share options or cash payment at the director's election. The option awards and cash payments were established at competitive levels taking into account peer data from comparable companies provided in a benchmarking survey undertaken by Radford consultants and are compliant with the last Directors' Remuneration policy approved by our shareholders.

        Our Non-Executive Directors do not receive any pension from the Company nor do they participate in any performance-related incentive plans. Our Non-Executive Directors participate in the Group's long-term incentive plans on terms similar to those used for Executive Directors. In accordance with their Letters of Appointment, all Non-Executive Directors (except for Barbara Duncan, Giles Kerr and Tal Zaks) were granted an annual award of share options on August 11, 2016. Ms. Duncan, Mr. Kerr and Dr. Zaks were awarded share options on joining the Board of Directors and relevant committees during 2016. Each Non-Executive Director is entitled to receive an annual award of share options, with such number to be determined by the Board.

        In determining option awards, the Board of Directors works within benchmarking guidelines provided by remuneration consultants. All options are granted with an exercise price that is no lower than the fair market value of an ordinary share on the date prior to the date of grant and options awarded to new directors become exercisable over three years while options awarded annually are exercisable on the first anniversary of the date of grant.

2016 Director Compensation Table

        The table below shows the compensation paid to our Non-Executive Directors during the year ended December 31, 2016. The compensation paid to James Noble, our Chief Executive Officer and an executive director is set forth in the "Summary Compensation Table" above.

Name
  Fees
Earned
or paid in
cash$(1)
  Option
awards($)(2)
  Total ($)  

David M. Mott(3)

        141,063     141,063  

Lawrence Alleva(4)

        144,945     144,945  

Ali Behbahani(4)

        136,016     136,016  

Barbara Duncan(5)

        295,099     295,099  

Giles Kerr(6)

    7,166     134,489     141,655  

Jonathan Knowles(7)

        160,085     160,085  

Ian Laing(8)

    17,209     106,123     123,332  

Elliott Sigal(9)

        136,016     136,016  

Peter Thompson(10)

        137,180     137,180  

Tal Zaks(11)

    5,217     134,489     139,706  

(1)
The fees paid to Mr. Kerr and Mr. Laing were denominated in pounds sterling. For purposes of this table, the 2016 amounts paid to those Directors have been converted based on the pound sterling/U.S. dollar exchange rate in effect as of December 31, 2016(£1/$1.233). All fees paid represent pro rated amounts as Mr. Kerr joined the Board on November 1, 2016, Dr, Zaks joined the Board on November 16, 2016 and Mr. Laing was paid effective from August 11, 2016 and resigned from the Board on December 31, 2016.

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(2)
See Item 7—"Share based compensation" and in Note 2 (r) and Note 10 "Share based compensation" to our audited consolidated financial statements, in our Form 10-K for an explanation of the assumptions used in the calculation of these amounts.

(3)
Mr. Mott received an annual option award covering 191, 410 ordinary shares on August 11, 2016.

(4)
Mr. Alleva received an annual option award covering 196,678 ordinary shares on August 11, 2016.

(5)
Ms. Duncan received an initial option award covering 332,776 ordinary shares on June 23, 2016.

(6)
Mr. Kerr received an initial option award covering 288,000 ordinary shares on November 29, 2016.

(7)
Dr. Knowles received an annual option award covering 217,222 ordinary shares on August 11, 2016.

(8)
Mr. Laing received an annual option award covering 144,000 ordinary shares on August 11, 2016.

(9)
Dr. Sigal received an annual option award covering 184,562 ordinary shares on August 11, 2016.

(10)
Dr. Thompson received an annual option award covering 186,142 ordinary shares on August 11, 2016.

(11)
Dr. Zaks received an initial option award covering 288,000 ordinary shares on November 29, 2016.

        In 2016, our Board of Directors met 14 times. With the exception of Ms. Duncan, Mr. Kerr and Dr. Zaks, all of our directors attended a minimum of 75% of the meetings of our Board of Directors and its committees during their membership on the board. Ms. Duncan was first appointed in late June and has attended six meetings in 2016. Mr. Kerr was appointed on November 1, 2016, and attended one meeting in 2016. Dr. Zaks was appointed on November 14, 2016, and was unable to attend the final board meeting of 2016; however, he has attended board and Remuneration Committee meetings in January through March 2017.

Deeds of Indemnification

        We do not have any third party indemnification provisions in place for the benefit of one or more of our directors. However, we agree to use all reasonable endeavors to provide and maintain appropriate directors' and officers' liability insurance (including ensuring that premiums are properly paid) for their benefit for so long as any claims may lawfully be brought against them.

Non-Executive Director Appointment Letters

        We have entered into letters of appointment with each of our Non-Executive Directors. These letters set forth the main terms on which each of our Non-Executive Directors serve on our Board of Directors. Continued appointment under the letter is contingent on continued satisfactory performance as a member of the Board of Directors and as a member of a committee, if relevant, as well as being re-elected at the annual general meetings in accordance with the Articles of Association of the Company. The appointment may be terminated by the Company or the Non-Executive Director with a three months' prior written notice. Upon termination, the Non-Executive Director is entitled to a pro-rata amount of the annual fee (if applicable) that is outstanding and payable up to the date of termination, and reimbursement in the normal way of any expenses properly incurred before that date.

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Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

        The following table and related footnotes set forth information with respect to the beneficial ownership of our ordinary shares, as of March 20, 2017, by:

        Beneficial ownership is determined in accordance with the rules and regulations of the SEC. Under these rules, beneficial ownership includes any shares as to which a person has sole or shared voting power or investment power. In computing the number of ordinary shares beneficially owned by a person and the percentage ownership of that person, ordinary shares subject to options, or other rights held by such person that are currently exercisable or will become exercisable within 60 days of March 20, 2017 are considered outstanding. These ordinary shares, however, are not included in the computation of the percentage ownership of any other person. Applicable percentage ownership is based on 424,775,092 ordinary shares outstanding as of March 20, 2017.

        Unless otherwise indicated, the address for each of the shareholders listed in the table below is c/o Adaptimmune Therapeutics plc, 101 Park Drive, Milton Park, Oxfordshire OX14 4RY, United Kingdom.

 
  Ordinary Shares
Beneficially Owned
 
Name of Beneficial Owner
  Number   Percent  

Greater than 5% Shareholders

             

New Enterprise Associates(1)

    59,286,000     13.96  

FMR LLC(2)

    42,391,084     9.98  

OrbiMed Private Investments V, L.P.(3)

    29,753,404     7.00  

Ian Laing(4)

    29,346,675     6.91  

Nicholas Cross(5)

    29,322,178     6.90  

Immunocore Limited

    26,976,700     6.35  

Capital World Investors(6)

    26,882,916     6.33  

George Robinson(7)

    22,896,520     5.39  

Named Executive Officers and Directors

             

James Noble(8)

    15,466,404     3.64  

Rafael Amado, M.D(9). 

    2,359,315     0.56  

Adrian Rawcliffe(10)

    2,263,315     0.53  

David Mott(11)

    59,449,229     14.00  

Ali Behbahani, M.D.(12)

    59,441,682     13.99  

Peter Thompson, M.D.(13)

    29,909,086     7.04  

Elliott Sigal, M.D., Ph.D.(14)

    673,012     0.16  

Lawrence M. Alleva(15)

    382,707     0.09  

Barbara Duncan(16)

         

Giles Kerr(16)

         

Tal Zaks, Ph.D.(16)

         

All Executive Officers and Directors as a Group (14 persons)

    117,129,449     27.57 %

(1)
Consists of (i) 59,269,000 ordinary shares directly held by New Enterprise Associates 14, L.P., or NEA 14 and (ii) 17,000 ordinary shares directly held by NEA Ventures 14, L.P., or NEA Ven 14. These ordinary shares are represented by ADSs. The shares directly held by NEA 14 are indirectly held by NEA Partners 14, L.P., or NEA Partners 14, the sole general partner of NEA 14, NEA 14 GP, LTD, or NEA 14 LTD, the sole general partner

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(2)
FMR LLC holds these shares in the form of ADSs on behalf of certain of its direct and indirect subsidiaries and has sole voting power and sole dispositive power over these shares. The registered office of FMR, LLC is 245 Summer Street, Boston, MA 02210, United States.

(3)
OrbiMed Capital GP V LLC ("GP V") is the sole general partner of OPI V. OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of GP V. GP V and OrbiMed Advisors may be deemed to have beneficial ownership of the shares held by OPI V. Samuel D. Isaly is the managing member of and owner of a controlling interest in OrbiMed Advisors and as such may be deemed to have beneficial ownership of the shares held by OPI V. Peter Thompson, one of our directors, is employed as a Private Equity Partner at OrbiMed Advisors. Each of GP V, OrbiMed Advisors, Mr. Isaly and Dr. Thompson disclaims beneficial ownership of the shares held by OPI V except to the extent of its or his pecuniary interest therein, if any. The address for these entities is 601 Lexington Avenue, 54th floor, New York, New York 10022.

(4)
Includes options held by Mr. Laing to purchase 303,875 ordinary shares that are exercisable immediately.

(5)
Includes 279,378 ordinary shares represented by 46,563 ADSs.

(6)
Capital World Investors holds these shares in the form of ADSs. Capital World Investors, a division of Capital Research and Management Company (CRMC), a U.S.—based investment management company, holds these shares in the form of ADSs. The Capital Group Companies, Inc. is the parent company of CRMC. The business address for CRMC is 333 South Hope Street, Los Angeles, CA 90071.

(7)
Includes 7,053,720 ordinary shares represented by 1,175,620 ADSs.

(8)
Consists of (i) 9,972,600 ordinary shares; (ii) 1,200,000 ordinary shares represented by 200,000 ADSs and (ii) options to purchase 4,293,804 ordinary shares that are or will be exercisable within 60 days of March 20, 2017'

(9)
Consists of (i) 96,000 ordinary shares represented by 16,000 ADSs and (ii) options to purchase 2,263,315 ordinary shares that are or will be exercisable within 60 days of March 20, 2017.

(10)
Consists of options to purchase 2,263,315 ordinary shares that are or will be exercisable within 60 days of March 20, 2017.

(11)
Includes the shares set forth in footnote (1) above and options held by Mr. Mott to purchase 163,229 ordinary shares that are exercisable immediately. Mr. Mott is a member of the Board at NEA 14 GP, LTD, which has ultimate voting and investment power over shares held of record by New Enterprise Associates 14, Limited Partnership. He disclaims beneficial ownership of such shares except to the extent of any pecuniary interest therein.

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(12)
Includes the shares set forth in footnote (1) above and options held by Dr. Behbahani to purchase 155,682 ordinary shares that are exercisable immediately. Dr. Behbahani is a partner of New Enterprise Associates, Inc., which has ultimate voting and investment power over shares held of record by New Enterprise Associates 14, Limited Partnership.

(13)
Includes the shares set forth in footnote (3) above and options held by Dr. Thompson to purchase 155,682 ordinary shares that are exercisable immediately. Dr. Thompson is an employee of Orbimed Advisors LLC, which has ultimate voting and investment power over shares held of record by Orbimed Private Investments V, L.P.

(14)
Includes shares held by Sigal Family Investments, LLC, and options held by Dr. Sigal to purchase 305,974 ordinary shares that are or will be exercisable within 60 days of March 20, 2017. Dr. Sigal is a manager of Sigal Family Investments, LLC. Dr. Sigal may be deemed to have voting and investment power over the shares held by Sigal Family Investments, LLC. Dr. Sigal disclaims beneficial ownership of such shares except to the extent of any pecuniary interest therein. Also included in the ordinary shares beneficially owned are 52,938 ordinary shares represented by 8,823 ADSs that Dr. Sigal purchased during the IPO.

(15)
Consists of options held by Mr. Alleva to purchase 312,123 ordinary shares that are or will be exercisable within 60 days of March 20, 2017 and 70,584 ordinary shares represented by 11,764 ADSs that Mr. Alleva purchased during the IPO.

(16)
The options held by Barbara Duncan, Giles Kerr and Tal Zaks are not exercisable within 60 days of March 20, 2017.

Equity Compensation Plan Information

        The following table provides information on our equity compensation plans as of December 31, 2016.

Plan Category
  Number of
Securities to be
Issued Upon
Exercise of
Outstanding
Options
  Weighted
Average
Exercise Price
of Outstanding
Options
$(1)
  Number of Securities
Available for
Future Issuance
Under Equity
Compensation
Plans(1)
 

Equity compensation plans

    49,237,290     0.72     33,128,439  

Total

    49,237,290     0.72     33,128,439  

(1)
For purposes of this table, the Weighted Average Exercise Price of Outstanding Options has been converted from £0.58 based on the pound sterling/U.S. dollar exchange rate in effect as of December 31, 2016 (£1/$1.233).

        The Company grants options over ordinary shares in Adaptimmune Therapeutics plc under the following option plans: (i) the Adaptimmune Therapeutics plc Employee Share Option Scheme (adopted January 14, 2016), (ii) the Adaptimmune Therapeutics plc 2015 Share Option Scheme and (adopted March 16, 2015) and (iii) the Adaptimmune Therapeutics plc Company Share Option Plan (adopted March 16, 2015). The maximum aggregate number of options which may be granted under these plans and any incentive plans adopted by the Company cannot exceed a scheme limit that equates to 8% of the initial fully diluted share capital of the Company immediately following our IPO plus an automatic annual increase of an amount equivalent to 4% of the issued share capital on each June 30 (or such lower number as the Board, or an appropriate committee of the Board, may determine). The automatic increase is effective from July 1, 2016.

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        Prior to December 31, 2014, the Company granted options to purchase ordinary shares in Adaptimmune Limited under three option schemes: (i) the Adaptimmune Limited Share Option Scheme (adopted May 30, 2008), (ii) the Adaptimmune Limited 2014 Share Option Scheme (adopted April 11, 2014) and (iii) the Adaptimmune Limited Company Share Option Plan (adopted December 16, 2014). As part of the corporate reorganization in connection with our IPO, the holders of options granted under these schemes over ordinary shares of Adaptimmune Limited were granted equivalent options on substantially the same terms over ordinary shares of Adaptimmune Therapeutics plc in exchange for the release of these options. The Company does not intend to grant any further options under these schemes. Further details of our share option plans are set forth in Note 10 titled "Share-based compensation" in our audited consolidated financial statements incorporated by reference in this prospectus supplement.

Certain Relationships and Related Party Transactions

Related Person Transactions Policy

        We have adopted a policy with respect to the review, approval and ratification of related party transactions. Under the policy, our Audit Committee will be responsible for reviewing and approving related person transactions. In the course of its review and approval of related person transactions, our Audit Committee will consider the relevant facts and circumstances to decide whether to approve such transactions. In particular, our policy will require our Audit Committee to consider, among other factors it deems appropriate:

        The Audit Committee may only approve those transactions that are in, or are not inconsistent with, our best interests and those of our shareholders, as the Audit Committee determines in good faith. If Audit Committee review and approval would be inappropriate, the relevant related party transaction will be referred to another independent body of our Board for review, consideration, approval or ratification.

Certain Related Person Transactions

        The following is a description of transactions since the beginning of 2016 in which (a) we were a participant, (b) the amount involved exceeded $120,000 and (c) one or more of our executive officers, directors, director nominees or 5% shareholders, or their immediate family members, each of whom we refer to as a "related person," had a direct or indirect material interest. We refer to these as "related person transactions." The information below excludes compensation arrangements with directors and executive officers, which are described above elsewhere in this prospectus supplement under "Executive Compensation."

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Investors Rights Agreement

        We are party to an investors rights agreement entered into on February 23, 2015, with certain of our shareholders, including New Enterprise Associates 14, L.P., NEA Ventures 2014, L.P., OrbiMed Private Investments V, L.P. and Sigal Family Investments, LLC pursuant to which certain of our shareholders, including certain holders with beneficial ownership of five percent or more of our ordinary shares and entities affiliated with certain of our directors, have the right to demand that we file a registration statement for their ordinary shares or request that their ordinary shares be covered by a registration statement that we are otherwise filing.

Principal Accountant Fees and Services

        The table below sets forth the fees paid to KPMG LLP over the past two years in connection with its work for us, including our subsidiary, Adaptimmune LLC. All such audit, audit-related and tax services were pre-approved by the Audit Committee, which concluded that the provision of such services by KPMG LLP was compatible with the maintenance of that firm's independence in the conduct of its auditing functions.

Fees
  December 31, 2015
($)(1)
  December 31, 2016
($)
 

Audit Fees

    212,000     360,000  

Audit-related Fees

    151,000     352,000  

Tax Fees

         

All Other Fees

    10,000      

Total

    163,000     712,000  

(1)
On July 1, 2015 we changed our fiscal year from June 30 to a calendar fiscal year. The fees for the period ending December 31, 2015 in the table above have been calculated by adding the fees paid for the six months ended June 30, 2015 and the six months ended December 31, 2015. Fees paid for the six months ended June 30, 2015 have been calculated by prorating the amounts paid for the year by the six month period.

Audit Fees

        Audit fees consist of fees billed for the audit of our annual consolidated financial statements, the review of the interim consolidated financial statements, and related services that are normally provided in connection with registration statements, including the registration statement for our initial public offering. Included in the 2015 audit fees are the fees billed in connection with our initial public offering in May 2015.

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Audit-Related Fees

        Audit- related fees incurred were $352,000 and $151,000 in 2016 and 2015, respectively.

Tax Fees

        Tax fees consist of fees for professional services, including tax consulting and compliance. There were no such fees incurred in 2016 or 2015.

All Other Fees

        We incurred $10,000 for all other fees in 2015, but did not incur any such fees in 2016.

Audit Committee Pre-Approval Policy and Procedures

        Our Audit Committee has reviewed and discussed with management our audited consolidated financial statements for the year ended December 31, 2016. Our Audit Committee has also discussed with KPMG LLP, our independent registered public accounting firm, the matters required to be discussed by Statement on Auditing Standards No. 61, as amended, regarding communication with audit committees, as adopted by the Public Company Accounting Oversight Board ("PCAOB") in Rule 3200T.

        Our Audit Committee has also received the written disclosures and the letter from KPMG LLP required by the applicable requirements of the PCAOB regarding communications with the audit committee concerning independence, and our Audit Committee has discussed with KPMG LLP its independence from management and the Company.

        Based on our Audit Committee's review and discussions with management and the independent auditors, and subject to the limitations of the Audit Committee's role and responsibilities referred to above and in the Audit Committee charter, our Audit Committee recommended to the Board of Directors that our audited consolidated financial statements be included in our Annual Report on Form 10-K for the year ended December 31, 2016 for filing with the SEC.

        The Audit Committee approves KPMG LLP's and its affiliates audit and non-audit services in advance as required under Sarbanes-Oxley and SEC rules. Before the commencement of each fiscal year, the Audit Committee appoints the independent auditor to perform audit services that we expect to be performed for the fiscal year and appoints the auditor to perform audit-related, tax and other permitted non-audit services. In addition, our Audit Committee approves the terms of the engagement letter to be entered into by us with the independent auditor. The Audit Committee has also delegated to its chairman the authority, from time to time, to pre-approve audit-related and non-audit services not prohibited by law to be performed by our independent auditors and associated fees, provided that the chairman shall report any decisions to pre-approve such audit-related and non-audit services and fees to our full Audit Committee at its next regular meeting.

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TAXATION

U.K. Tax Considerations

        The following is a general summary of certain limited U.K. tax considerations relating to the ownership and disposal of the ordinary shares or the ADSs and does not address all possible tax consequences relating to an investment in the ordinary shares or the ADSs. It is based on current U.K. tax law and published HM Revenue & Customs ("HMRC"), practice as of the date hereof, both of which are subject to change, possibly with retrospective effect.

        Except as provided otherwise, this summary applies only to persons who are resident (and, in the case of individuals, domiciled) in the United Kingdom for tax purposes and who are not resident for tax purposes in any other jurisdiction, and do not have a permanent establishment or fixed base in any other jurisdiction with which the holding of the ordinary shares or the ADSs is connected ("U.K. Holders"). Persons (a) who are not resident (or, if resident, are not domiciled) in the United Kingdom for tax purposes, including those individuals and companies who trade in the United Kingdom through a branch, agency or permanent establishment in the United Kingdom to which the ordinary shares or the ADSs are attributable, or (b) who are resident or otherwise subject to tax in a jurisdiction outside the United Kingdom, are recommended to seek the advice of professional advisors in relation to their taxation obligations.

        This summary is for general information only and is not intended to be, nor should it be considered to be, legal or tax advice to any particular investor. It does not address all of the tax considerations that may be relevant to specific investors in light of their particular circumstances or to investors subject to special treatment under U.K. tax law. In particular:

        This summary further assumes that a holder of ADSs is the beneficial owner of the underlying ordinary shares for U.K. tax purposes.

        POTENTIAL INVESTORS IN THE ADSs SHOULD SATISFY THEMSELVES PRIOR TO INVESTING AS TO THE OVERALL TAX CONSEQUENCES, INCLUDING, SPECIFICALLY, THE CONSEQUENCES UNDER U.K. TAX LAW AND HMRC PRACTICE OF THE ACQUISITION, OWNERSHIP AND DISPOSAL OF THE ORDINARY SHARES OR ADSs IN THEIR OWN PARTICULAR CIRCUMSTANCES BY CONSULTING THEIR OWN TAX ADVISERS.

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        Dividend payments in respect of the ordinary shares represented by the ADSs may be made without withholding or deduction for or on account of U.K. tax.

        Dividends received by individual U.K. Holders will be subject to U.K. income tax on the amount of the dividend paid.

        An individual U.K. Holder will be exempt from U.K. income tax (by applying a nil rate of tax) on the first £5,000 of dividend income received by such individual U.K. Holder in a tax year, regardless of the amount of the individual's other taxable income. It is noted that a legislative measure has been announced (but not yet finalized) to change the amount of dividend income in a tax year that is charged at the nil rate of tax from the first £5,000 to the first £2,000, with effect from April 6, 2018.

        Dividend income in excess of the £5,000 allowance will be taxed at the rate of 7.5% to the extent that the dividend, when treated as the top slice of the relevant U.K. Holder's income, does not exceed the basic rate income tax limit; at the rate of 32.5% to the extent that the dividend, when treated as the top slice of the relevant U.K. Holder's income, exceeds the basic rate income tax limit but does not exceed the higher rate income tax limit; and at the rate of 38.1% to the extent that the dividend, when treated as the top slice of the relevant U.K. Holder's income, exceeds the higher rate income tax limit.

        An individual holder of ordinary shares or ADSs who is not a U.K. Holder will not be chargeable to U.K. income tax on dividends paid by the company, unless such holder carries on (whether solely or in partnership) a trade, profession or vocation in the United Kingdom through a branch or agency in the United Kingdom to which the ordinary shares or the ADSs are attributable. In these circumstances, such holder may, depending on his or her individual circumstances, be chargeable to U.K. income tax on dividends received from the company.

        A U.K. Holder within the charge to U.K. corporation tax may be entitled to exemption from U.K. corporation tax in respect of dividend payments. If the conditions for the exemption are not satisfied, or such U.K. Holder elects for an otherwise exempt dividend to be taxable, U.K. corporation tax will be chargeable on the gross amount of any dividends. If potential investors are in any doubt as to their position, they should consult their own professional advisers.

        A corporate holder of ordinary shares or ADSs that is not a U.K. Holder will not be subject to U.K. corporation tax on dividends received from the Company, unless it carries on a trade in the United Kingdom through a permanent establishment to which the ordinary shares or the ADSs are attributable. In these circumstances, such holder may, depending on its individual circumstances and if the exemption from U.K. corporation tax discussed above does not apply, be chargeable to U.K. corporation tax on dividends received from the Company.

        A disposal or deemed disposal of ordinary shares or ADSs by an individual U.K. Holder may, depending on his or her individual circumstances, give rise to a chargeable gain or to an allowable loss for the purpose of U.K. capital gains tax. The principal factors that will determine the capital gains tax position on a disposal of ordinary shares or ADSs are the extent to which the holder realizes any other capital gains in the tax year in which the disposal is made, the extent to which the holder has incurred

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capital losses in that or any earlier tax year and the level of the annual allowance of tax-free gains in that tax year (the "annual exemption"). The annual exemption for the 2016/2017 tax year is £11,100. If, after all allowable deductions, an individual U.K. Holder's total taxable income for the year (which, for the avoidance of doubt, will include any dividend income within the £5,000 nil rate band described above) exceeds the basic rate income tax limit, a taxable capital gain accruing on a disposal of ordinary shares or ADSs will be taxed at 20%. If, after all allowable deductions, an individual U.K. Holder's total taxable income for the year does not exceed the basic rate income tax limit, and assuming the individual does not have any other taxable capital gains in the tax year that would use up the remaining basic rate allowance, a taxable capital gain accruing on a disposal of ordinary shares or ADSs will be taxed at 10% on an amount that, when treated as the top slice of the relevant U.K. Holder's income/gains, does not exceed the basic rate income tax limit and at 20% on the remainder.

        An individual U.K. Holder who ceases to be resident in the United Kingdom (or who fails to be regarded as resident in a territory outside the United Kingdom for the purposes of double taxation relief) for a period of less than five years and who disposes of his or her ordinary shares or ADSs during that period of temporary non-residence may be liable to U.K. capital gains tax on a chargeable gain accruing on such disposal on his or her return to the United Kingdom (or upon ceasing to be regarded as resident outside the United Kingdom for the purposes of double taxation relief) (subject to available exemptions or reliefs).

        A disposal (or deemed disposal) of ordinary shares or ADSs by a corporate U.K. Holder may give rise to a chargeable gain or an allowable loss for the purpose of U.K. corporation tax. Such a holder should be entitled to an indexation allowance, which applies to reduce capital gains to take account of inflation. The allowance may reduce a chargeable gain but will not create or increase an allowable loss.

        Any gains or losses in respect of currency fluctuations over the period of holding the ordinary shares or ADSs would also be brought into account on the disposal.

        An individual holder who is not a U.K. Holder will not be liable to U.K. capital gains tax on capital gains realized on the disposal of his or her ordinary shares or ADSs unless such holder carries on (whether solely or in partnership) a trade, profession or vocation in the United Kingdom through a branch or agency in the United Kingdom to which the ordinary shares or ADSs are attributable. In these circumstances, such holder may, depending on his or her individual circumstances, be chargeable to U.K. capital gains tax on chargeable gains arising from a disposal of his or her ordinary shares or ADSs.

        A corporate holder of ordinary shares or ADSs that is not a U.K. Holder will not be liable for U.K. corporation tax on chargeable gains realized on the disposal of its ordinary shares or ADSs unless it carries on a trade in the United Kingdom through a permanent establishment to which the ordinary shares or ADSs are attributable. In these circumstances, a disposal (or deemed disposal) of ordinary shares or ADSs by such holder may give rise to a chargeable gain or an allowable loss for the purposes of U.K. corporation tax.

        If, for the purposes of the Taxes on Estates of Deceased Persons and on Gifts Treaty 1978 between the United States and the United Kingdom, an individual holder of ordinary shares or ADSs is domiciled in the United States and is not a national of the United Kingdom, any ordinary shares or ADSs beneficially owned by that holder will not generally be subject to U.K. inheritance tax on that holder's death or on a gift made by that holder during his/her lifetime, provided that any applicable U.S. federal gift or estate tax liability is paid, except where (i) the ordinary shares or ADSs are part of the business property of a U.K. permanent establishment or pertain to a U.K. fixed base used for the

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performance of independent personal services; or (ii) the ordinary shares or ADSs are comprised in a settlement unless, at the time the settlement was made, the settlor was domiciled in the United States and not a national of the United Kingdom (in which case no charge to U.K. inheritance tax should apply).

        No U.K. stamp duty is payable on the issue of the ordinary shares.

        Based on current published HMRC practice and recent case law, there should be no U.K. stamp duty reserve tax ("SDRT") payable on the issue of ordinary shares to a depositary receipt system or a clearance service (for example DTC).

        Transfers of ordinary shares to, or to a nominee or agent for, a person whose business is or includes issuing depositary receipts or to, or to a nominee or agent for, a person whose business is or includes the provision of clearance services, will generally be regarded by HMRC as subject to stamp duty or SDRT at 1.5% of the amount or value of the consideration or, in certain circumstances, the value of the ordinary shares transferred. In practice, this liability for stamp duty or SDRT is in general borne by such person depositing the relevant shares in the depositary receipt system or clearance service. Transfers of ordinary shares between depositary receipt systems and clearance services will generally be exempt from stamp duty and SDRT.

        The transfer on sale of ordinary shares by a written instrument of transfer will generally be liable to U.K. stamp duty at the rate of 0.5% of the amount or value of the consideration for the transfer. The purchaser normally pays the stamp duty.

        An agreement to transfer ordinary shares outside a depositary receipt system or a clearance service will generally give rise to a liability on the purchaser to SDRT at the rate of 0.5% of the amount or value of the consideration. Such SDRT is payable on the seventh day of the month following the month in which the charge arises, but where an instrument of transfer is executed and duly stamped before the expiry of a period of six years beginning with the date of that agreement, (i) any SDRT that has not been paid ceases to be payable, and (ii) any SDRT that has been paid may be recovered from HMRC, generally with interest.

        We do not expect that HMRC will consider any liability to U.K. stamp duty or SDRT to have arisen in relation to the deposit with the custodian or the depositary of the ordinary shares offered by us pursuant to this offering. However, a liability to U.K. stamp duty or SDRT may, depending on the circumstances, arise in respect of the deposit with the custodian or the depositary of ordinary shares where ordinary shares are transferred to the custodian or the depositary otherwise than as an integral part of an issue of share capital.

Transfer of ADSs

        Based on current HMRC published practice, no U.K. stamp duty should be payable on a written instrument transferring an ADS or on a written agreement to transfer an ADS, as an ADS is not regarded as "stock" or a "marketable security" for U.K. stamp duty purposes.

        No SDRT will be payable in respect of an agreement to transfer an ADS, as an ADS is not considered to be a "chargeable security" for the purposes of SDRT.

        The statements above in relation to stamp duty and SDRT apply irrespective of whether the relevant holder of ordinary shares or ADSs is resident or domiciled in the United Kingdom.

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U.S. Federal Income Taxation

        The following discussion describes the material U.S. federal income tax consequences to U.S. Holders (as defined below) under present law of the purchase, ownership and disposition of the ADSs. This discussion is based on the U.S. Internal Revenue Code of 1986, as amended (or the "Code" for purposes of this discussion), in effect as of the date of this prospectus supplement and on U.S. Treasury regulations in effect or, in some cases, proposed, as of the date of this prospectus supplement, as well as judicial and administrative interpretations thereof available on or before such date. All of the foregoing authorities are subject to change, which change could apply retroactively and could affect the tax consequences described below.

        This discussion applies only to U.S. Holders that hold the ADSs as capital assets for U.S. federal income tax purposes. It does not purport to be a comprehensive description of all tax considerations that may be relevant to a decision to purchase the ADSs by any particular investor. In particular, this discussion does not address tax considerations applicable to a U.S. Holder that may be subject to special tax rules, including, without limitation, a dealer in securities or currencies, a trader in securities that elects to use a mark-to-market method of accounting for securities holdings, banks, thrifts, or other financial institutions, an insurance company, a tax-exempt organization, a person that holds the ADSs as part of a hedge, straddle or conversion transaction for tax purposes, a person whose functional currency for tax purposes is not the U.S. dollar, certain former citizens or residents of the United States or a person that owns or is deemed to own 10% or more of the company's voting shares. Moreover, this description does not address the U.S. federal estate, gift, or alternative minimum tax consequences, or any state, local or non-U.S. tax consequences, of the acquisition, ownership and disposition of the ADSs. In addition, the discussion does not address tax consequences to an entity treated as a partnership for U.S. federal income tax purposes that holds the ADSs, or a partner in such partnership. The U.S. federal income tax treatment of each partner of such partnership generally will depend upon the status of the partner and the activities of the partnership. Prospective purchasers that are partners in a partnership holding the ADSs are urged to consult their own tax advisers.

        The discussion below of the U.S. federal income tax consequences to "U.S. Holders" will apply to an investor that is a beneficial owner of ADSs and that is, for U.S. federal income tax purposes,

        For U.S. federal income tax purposes, a beneficial owner of ADSs generally will be treated as the owner of the underlying ordinary shares represented by such ADSs. Accordingly, deposits or withdrawals of the underlying ordinary shares for ADSs generally will not be subject to U.S. federal income tax.

        Prospective purchases are urged to consult their tax advisors about the application of the U.S. federal income tax rules to their particular circumstances as well as the state, local, non-U.S. and other tax consequences to them of the purchase, ownership and disposition of the ADSs.

        Subject to the PFIC rules discussed below, the gross amount of distributions made by us to a U.S. Holder with respect to the ADSs, before reduction for any non-U.S. taxes withheld therefrom, will be

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includable in gross income as dividend income to the extent that such distribution is paid out of our current or accumulated earnings and profits (as determined under U.S. federal income tax principles). To the extent, if any, that the amount of any cash distribution exceeds our current and accumulated earnings and profits, it will be treated, first as, a tax-free return of such U.S. Holder's tax basis in its ADSs, and to the extent the amount of the distribution exceeds such U.S. Holder's tax basis, the excess will be taxed as capital gain. We do not intend to calculate our earnings and profits under U.S. federal income tax principles. Therefore, a U.S. Holder should expect that a distribution will generally be treated as a dividend even if that distribution would otherwise be treated as a non-taxable return of capital or as capital gain under the rules described above. A dividend in respect of the ADSs will not be eligible for the dividends-received deduction allowed to corporations in respect of dividends received from other U.S. corporations. Non-corporate U.S. Holders may qualify for the lower rates of taxation with respect to dividends on ADSs applicable to long term capital gains (i.e., gains from the sale of capital assets held for more than one year), provided that certain conditions are met, including certain holding period requirements and the absence of certain risk reduction transactions. Moreover, such reduced rate shall not apply if we are a PFIC for the taxable year in which we pay a dividend, or were a PFIC for the preceding taxable year.

        Subject to the paragraph below, dividends generally will constitute income from sources outside the United States, which may be relevant in calculating a U.S. Holder's foreign tax credit limitation. Subject to certain conditions and limitations, non-U.S. tax withheld, if any, on dividends may be deducted from such U.S. Holder's taxable income or credited against such U.S. Holder's U.S. federal income tax liability. The limitation on foreign taxes eligible for credit is calculated separately with respect to specific classes of income. For this purpose, dividends that we distribute generally should constitute "passive category income," or, in the case of certain U.S. Holders, "general category income." A foreign tax credit for foreign taxes imposed on distributions may be denied if a U.S. Holder does not satisfy certain minimum holding period requirements.

        Notwithstanding the paragraph above, if 50% or more of the ADSs are treated as held by U.S. persons, we will be treated as a "U.S.-owned foreign corporation." In that case, dividends may be treated for U.S. foreign tax credit purposes as income from sources outside the United States to the extent paid out of our non-U.S. source earnings and profits, and as income from sources within the United States to the extent paid out of our U.S. source earnings and profits. There can be no assurance that we will not be treated as a U.S.-owned foreign corporation. If the dividends are taxed as qualified dividend income (as discussed above), the amount of the dividend taken into account for purposes of calculating the U.S. foreign tax credit limitation will generally be limited to the gross amount of the dividend, multiplied by the preferential rate divided by the highest rate of tax normally applicable to dividends. The rules relating to the determination of the foreign tax credit are complex, and U.S. Holders are urged to consult their tax advisors to determine whether and to what extent such U.S. Holder will be entitled to a foreign tax credit.

        U.S. Holders are urged to consult their tax advisors regarding the tax consequences of receiving, converting or disposing of any U.S. currency, received or deemed received as dividends on our ADSs or on the sale or retirement of an ADS.

        Subject to the PFIC rules discussed below, a U.S. Holder will recognize taxable gain or loss on any sale, exchange or other taxable disposition of an ADS equal to the difference between the amount realized (in U.S. dollars) for the ADS and such U.S. Holder's tax basis (in U.S. dollars) in the ADS.

        The gain or loss will generally be capital gain or loss. A non-corporate U.S. Holder that has held the ADS for more than one year, may be eligible for preferential tax rates. The deductibility of capital

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losses is subject to limitations. Any such gain or loss generally will be treated as U.S. source income or loss for U.S. foreign tax credit purposes.

        A Medicare contribution tax of 3.8% is imposed on a portion or all of the net investment income of certain individuals with a modified adjusted gross income of over $200,000 (or $250,000 in the case of joint filers or $125,000 in the case of married individuals filing separately) and on the undistributed net investment income of certain estates and trusts. For these purposes, "net investment income" generally includes income from any dividends paid with respect to ADSs and net gain from the sale, exchange or other taxable disposition of ADSs, reduced by any deductions properly allocable to such income or net gain. U.S. Holders are urged to consult their tax advisors regarding the applicability of this tax to their income and gains in respect of an investment in the ADSs.

        Special U.S. tax rules apply to U.S. Holders of shares of ADS of companies that are considered to be passive foreign investment companies, or PFICs. We will be classified as a PFIC in a particular taxable year if either (i) 75% or more of our gross income for the taxable year is passive income or (ii) on average at least 50% of the value of our assets produce passive income or are held for the production of passive income. Passive income for this purpose generally includes, among other things, certain dividends, interest, royalties, rents and gains from commodities and securities transactions and from the sale or exchange of property that gives rise to passive income. In making this determination, we will be treated as earning our proportionate share of any income and owning our proportionate share of any assets of any corporation in which we hold a 25% or greater interest (by value).

        Based on our estimated gross income, the average value of our assets, including goodwill, and the nature of our active business, we do not believe we were treated as a PFIC for U.S. federal income tax purposes for the U.S. taxable year ending December 31, 2016. Our status for any taxable year will depend on our assets and activities in each year, and because this is a factual determination made annually after the end of each taxable year, there can be no assurance that we will not be considered a PFIC for this year or any future taxable year. The market value of our assets may be determined in large part by reference to the market price of the ADSs, which is likely to fluctuate (and may fluctuate considerably given that market prices of life sciences companies can be especially volatile). Furthermore, because the value of our gross assets is likely to be determined in large part by reference to our market capitalization and the value of our goodwill, a decline in the value of our shares could affect the determination of whether we are a PFIC. A U.S. Holder may be able to mitigate some of the adverse U.S. federal income tax consequences described below with respect to owning the ADSs if we are classified as a PFIC for any taxable year, provided that such U.S. Holder is eligible to make, and validly makes a "mark-to-market" election, described below. In certain circumstances a U.S. Holder can make a "qualified electing fund" election to mitigate some of the adverse tax consequences described with respect to an ownership interest in a PFIC by including in income its share of the PFIC's income on a current basis. However, we do not currently intend to prepare or provide the information that would enable a U.S. Holder to make a qualified electing fund election.

        In the event that we are classified as a PFIC in any year in which a U.S. Holder holds the ADSs, and the "mark-to-market" election described in the following paragraph is not made by a taxable U.S. Holder, a special tax regime will apply with respect to such U.S. Holder to both (a) any gain realized on the sale or other disposition of the ADSs and (b) any "excess distribution" by us to such U.S. Holder (generally, such U.S. Holder's ratable portion of distributions received by such U.S. Holder in any year which are greater than 125% of the average annual distribution received by such U.S. Holder in the shorter of the three preceding years or such U.S. Holder's holding period for the ADSs). Any gain recognized by such U.S. Holder on a sale or other disposition (including a pledge) of the ADSs

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and any excess distribution would be allocated ratably over such U.S. Holder's holding period for the ADSs.

        The amounts allocated to the taxable year of the sale or other disposition and to any year before we became a PFIC would be taxed as ordinary income. The amount allocated to each other taxable year would be subject to tax at the highest rate in effect for individuals or corporations, as appropriate, for that taxable year, and the interest charge generally applicable to underpayments of tax would be imposed on taxes deemed to have been payable in for the relevant taxable PFIC years. Classification as a PFIC may also have other adverse tax consequences, including, in the case of U.S. Holders that are individuals, the denial of a step-up in the basis of such U.S. Holder's ADSs at death.

        If we are a PFIC for any taxable year during which a U.S. Holder holds the ADSs, then in lieu of being subject to the special tax regime and interest charge rules discussed above, a U.S. Holder may make an election to include gain on the ADSs as ordinary income under a mark-to-market method, provided that such the ADSs are treated as "regularly traded" on a "qualified exchange." In general, the ADSs will be treated as "regularly traded" for a given calendar year if more than a de minimis quantity of the ADSs are traded on a qualified exchange on at least 15 days during each calendar quarter of such calendar year. Although the U.S. Internal Revenue Service ("IRS") has not published any authority identifying specific exchanges that may constitute "qualified exchanges," Treasury Regulations provide that a qualified exchange is (a) a U.S. securities exchange that is registered with the Securities and Exchange Commission, (b) the U.S. market system established pursuant to section 11A of the Securities and Exchange Act of 1934, or (c) a non-U.S. securities exchange that is regulated or supervised by a governmental authority of the country in which the market is located, provided that (i) such non-U.S. exchange has trading volume, listing, financial disclosure, surveillance and other requirements designed to prevent fraudulent and manipulative acts and practices, to remove impediments to and perfect the mechanism of a free and open, fair and orderly, market, and to protect investors; and the laws of the country in which such non-U.S. exchange is located and the rules of such non-U.S. exchange ensure that such requirements are actually enforced and (ii) the rules of such non-U.S. exchange effectively promote active trading of listed shares. We have received approval to have the ADSs listed on The Nasdaq Global Select Market, which is a U.S. securities exchange that is registered with the SEC. However, no assurance can be given that the ADSs will meet the requirements to be treated as "regularly traded" for purposes of the mark-to-market election. In addition, because a mark-to-market election cannot be made for any lower-tier PFICs that we may own, a U.S. Holder may continue to be subject to the special tax regime with respect to such holder's indirect interest in any investments held by us that are treated as an equity interest in a PFIC for U.S. federal income tax purposes, including shares in any future subsidiary of ours that is treated as a PFIC.

        If a U.S. Holder makes this mark-to-market election, such U.S. Holder will be required in any year in which we are a PFIC to include as ordinary income the excess of the fair market value of such U.S. Holder's ADSs at year-end over its basis in those ADSs. In addition, the excess, if any, of such U.S. Holder's basis in the ADSs over the fair market value of such U.S. Holder's ADSs at year-end is deductible as an ordinary loss in an amount equal to the lesser of (i) the amount of the excess or (ii) the amount of the net mark-to-market gains that have been included in income in prior years by such U.S. Holder. Any gain recognized by such U.S. Holder upon the sale of such U.S. Holder's ADSs will be taxed as ordinary income in the year of sale. Amounts treated as ordinary income will not be eligible for the preferential tax rate applicable to qualified dividend income or long-term capital gains. A U.S. Holder's adjusted tax basis in the ADSs will be increased by the amount of any income inclusion and decreased by the amount of any deductions under the mark-to-market rules. If a U.S. Holder makes a mark-to market election, it will be effective for the taxable year for which the election

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is made and all subsequent taxable years unless the ADSs are no longer regularly traded on a qualified exchange or the IRS consents to the revocation of the election.

        U.S. Holders who hold or have held our ADSs during a period when we were or are a PFIC will be subject to the foregoing rules, even if we cease to be a PFIC in subsequent years, subject to exceptions for U.S. Holders who made a timely qualified electing fund election or mark-to-market election. The U.S. federal income tax rules relating to PFICs are complex. U.S. Holders are urged to consult their tax advisors with respect to the purchase, ownership and disposition of the ADSs, the availability of the mark-to-market election and whether making the election would be advisable in their particular circumstances, and the IRS information reporting obligations with respect to the purchase, ownership and disposition of the ADSs.

        Distributions with respect to ADSs and proceeds from the sale, exchange or disposition of ADSs may be subject to information reporting to the U.S. Internal Revenue Service, or IRS, and U.S. backup withholding rules. Backup withholding will not apply to a U.S. Holder who furnishes a correct taxpayer identification number and makes any other required certification or who is otherwise exempt from backup withholding. U.S. Holders who are required to establish their exempt status generally must provide such certification on U.S. Internal Revenue Service Form W-9. U.S. Holders are urged to consult their tax advisors regarding the application of the U.S. information reporting and backup withholding rules.

        Backup withholding is not an additional tax. Amounts withheld as backup withholding may be credited against a U.S. Holder's U.S. federal income tax liability, and a U.S. Holder may obtain a refund of any excess amounts withheld under the backup withholding rules by filing the appropriate claim for refund with the IRS and furnishing any required information.

        U.S. Holders who are either individuals or certain domestic entities may be required to submit certain information to the IRS with respect to such holder's beneficial ownership of the ADSs, if such ADSs are not held on such holder's behalf by a financial institution, as our ordinary shares are considered "specified foreign financial assets." Penalties and potential other adverse tax consequences may be imposed if a U.S. Holder is required to submit such information to the IRS and fails to do so. U.S. Holders are urged to consult their tax advisors regarding the potential information reporting obligations that may be imposed with respect to the ownership and disposition of the ADSs.

        The above description is not intended to constitute a complete analysis of all tax consequences relating to acquisition, ownership and disposition of the ADSs. Prospective purchases are urged to consult their tax advisors concerning the tax consequences related their particular circumstances.

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UNDERWRITING

        Citigroup Global Markets Inc., Cowen and Company, LLC and Leerink Partners LLC are acting as joint book-running managers of the offering and as representatives of the underwriters named below. Subject to the terms and conditions stated in the underwriting agreement dated the date of this prospectus supplement, each underwriter named below has severally agreed to purchase, and we have agreed to sell to that underwriter, the number of ordinary shares in the form of ADSs, set forth opposite the underwriter's name.

Underwriter
  Number of
ADSs

Citigroup Global Markets Inc. 

              

Cowen and Company, LLC

              

Leerink Partners LLC

              

Total

              

        The underwriters may elect to take delivery of all or a portion of the ordinary shares purchased in the form of ADSs. References in this section to ordinary shares include ADSs to the extent applicable.

        The underwriting agreement provides that the obligations of the underwriters to purchase the ADSs included in this offering are subject to approval of legal matters by counsel and to other conditions. The underwriters are obligated to purchase all the ADSs (other than those covered by the underwriters' option to purchase additional ADSs described below) if they purchase any of the ADSs. The offering price and the total underwriting discounts and commissions per ADS or per ordinary share are identical.

        ADSs sold by the underwriters to the public will initially be offered at the initial public offering price set forth on the cover of this prospectus supplement. Any ADSs sold by the underwriters to securities dealers may be sold at a discount from the initial public offering price not to exceed $            per ADS. If all the ADSs are not sold at the initial offering price, the underwriters may change the offering price and the other selling terms.

        If the underwriters sell more ADSs than the total number set forth in the table above, we have granted to the underwriters an option, exercisable for 30 days from the date of this prospectus supplement, to purchase up to            additional ADSs at the public offering price less the underwriting discount. To the extent the option is exercised, each underwriter must purchase a number of additional ADSs approximately proportionate to that underwriter's initial purchase commitment. Any ADSs issued or sold under the option will be issued and sold on the same terms and conditions as the other ADSs that are the subject of this offering.

        Pursuant to certain "lock-up" agreements, we and our executive officers and directors have agreed, subject to certain exceptions, not to offer, sell, assign, transfer, pledge, contract to sell, or otherwise dispose of or announce the intention to otherwise dispose of, or enter into any swap, hedge or similar agreement or arrangement that transfers, in whole or in part, the economic consequence of ownership of, directly or indirectly, or make any demand or request or exercise any right with respect to the registration of, or file with the SEC a registration statement under the Securities Act relating to, any ADSs, ordinary shares or any securities convertible into or exercisable or exchangeable for or representing ADSs or ordinary shares, without the prior written consent of Citigroup Global Markets Inc., Cowen and Company, LLC and Leerink Partners LLC for a period of 90 days after the date of the pricing of the offering.

        This lock-up provision applies to the ordinary shares and ADSs and to securities convertible into or exchangeable or exercisable for ordinary shares and ADSs. It also applies to ordinary shares and ADSs owned now or acquired later by the person executing the agreement or for which the person

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executing the agreement later acquires the power of disposition. The exceptions permit parties to the "lock-up" agreements, among other things and subject to restrictions, to: (a) make certain gifts, (b) make transfers to immediate family members, (c) make transfers to affiliates or to any investment fund or other entity controlled or managed by the party and (d) participate in tender offers, mergers, consolidations or other similar transactions made to all holders of the ADSs and/or ordinary shares involving a change of control of the Company. In addition, the lock-up provision will not restrict broker-dealers from engaging in market making and similar activities conducted in the ordinary course of their business.

        Citigroup Global Markets Inc., Cowen and Company, LLC and Leerink Partners LLC, in their sole discretion, may release our ordinary shares and ADSs subject to the lock-up agreements described above in whole or in part at any time. When determining whether or not to release our ordinary shares and ADSs from lock-up agreements, Citigroup Global Markets Inc., Cowen and Company, LLC and Leerink Partners LLC will consider, among other factors, the holder's reasons for requesting the release, the number of ordinary shares and ADSs for which the release is being requested and market conditions at the time of the request.

        The ADSs are listed on The Nasdaq Global Select Market under the symbol "ADAP".

        The following table shows the underwriting discounts and commissions that we are to pay to the underwriters in connection with this offering. These amounts are shown assuming both no exercise and full exercise of the underwriters' option to purchase additional ADSs.

 
  Paid by Adaptimmune  
 
  No Exercise   Full Exercise  

Per Ordinary Share

  $                $               

Per ADS

  $     $    

Total

  $     $    

        We estimate that our portions of the total expenses of this offering will be $            . We have also agreed to reimburse the underwriters for up to $25,000 for their FINRA counsel fee. In accordance with FINRA Rule 5110, this reimbursed fee is deemed underwriting compensation for this offering.

        In connection with the offering, the underwriters may purchase and sell ADSs in the open market. Purchases and sales of ADSs in the open market may include short sales, purchases to cover short positions, which may include purchases pursuant to the underwriters' option to purchase additional ADSs, and stabilizing purchases.

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        Purchases to cover short positions and stabilizing purchases, as well as other purchases by the underwriters for their own accounts, may have the effect of preventing or retarding a decline in the market price of the ADSs. They may also cause the price of the ADSs to be higher than the price that would otherwise exist in the open market in the absence of these transactions. The underwriters may conduct these transactions on The Nasdaq Global Select Market, in the over-the-counter market or otherwise. If the underwriters commence any of these transactions, they may discontinue them at any time.

        In addition, in connection with this offering, some of the underwriters (and selling group members) may engage in passive market making transactions in the ADSs on The Nasdaq Global Select Market, prior to the pricing and completion of the offering. Passive market making consists of displaying bids on The Nasdaq Global Select Market no higher than the bid prices of independent market makers and making purchases at prices no higher than those independent bids and effected in response to order flow. Net purchases by a passive market maker on each day are limited to a specified percentage of the passive market maker's average daily trading volume in the ADSs during a specified period and must be discontinued when that limit is reached. Passive market making may cause the price of the ADSs to be higher than the price that otherwise would exist in the open market in the absence of those transactions. If the underwriters commence passive market making transactions, they may discontinue them at any time.

Conflicts of Interest

        The underwriters are full service financial institutions engaged in various activities, which may include securities trading, commercial and investment banking, financial advisory, investment management, principal investment, hedging, financing and brokerage activities. The underwriters and their respective affiliates have in the past performed commercial banking, investment banking and advisory services for us from time to time for which they have received customary fees and reimbursement of expenses and may, from time to time, engage in transactions with and perform services for us in the ordinary course of their business for which they may receive customary fees and reimbursement of expenses. In the ordinary course of their various business activities, the underwriters and their respective affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (which may include bank loans and/or credit default swaps) for their own account and for the accounts of their customers and may at any time hold long and short positions in such securities and instruments. Such investments and securities activities may involve securities and/or instruments of ours or our affiliates. The underwriters and their affiliates may also make investment recommendations and/or publish or express independent research views in respect of such securities or financial instruments and may hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

        We have agreed to indemnify the underwriters against certain liabilities, including liabilities under the Securities Act, or to contribute to payments the underwriters may be required to make because of any of those liabilities.

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Notice to Prospective Investors in Canada

        The ADSs be sold only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited investors, as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the ADSs must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

        Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement (including any amendment thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser's province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser's province or territory for particulars of these rights or consult with a legal advisor.

        Pursuant to section 3A.3 of National Instrument 33-105 Underwriting Conflicts ("NI 33-105"), the underwriters are not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.

Notice to Prospective Investors in the European Economic Area

        In relation to each member state of the European Economic Area that has implemented the Prospectus Directive (each, a relevant member state), with effect from and including the date on which the Prospectus Directive is implemented in that relevant member state (the relevant implementation date), an offer of ADSs described in this prospectus supplement may not be made to the public in that relevant member state other than:

provided that no such offer of securities shall require us or any underwriter to publish a prospectus pursuant to Article 3 of the Prospectus Directive.

        For purposes of this provision, the expression an "offer of securities to the public" in any relevant member state means the communication in any form and by any means of sufficient information on the terms of the offer and the securities to be offered so as to enable an investor to decide to purchase or subscribe for the securities, as the expression may be varied in that member state by any measure implementing the Prospectus Directive in that member state, and the expression "Prospectus Directive" means Directive 2003/71/EC (and amendments thereto, including the 2010 PD Amending Directive, to the extent implemented in the relevant member state) and includes any relevant implementing measure in the relevant member state. The expression 2010 PD Amending Directive means Directive 2010/73/EU.

        The sellers of the ADSs have not authorized and do not authorize the making of any offer of ADSs through any financial intermediary on their behalf, other than offers made by the underwriters with a view to the final placement of the ADSs as contemplated in this prospectus supplement. Accordingly, no purchaser of the ADSs, other than the underwriters, is authorized to make any further offer of the ADSs on behalf of the sellers or the underwriters.

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Notice to Prospective Investors in the United Kingdom

        This prospectus supplement and the accompanying prospectus are only being distributed to, and is only directed at, persons in the United Kingdom that are qualified investors within the meaning of Article 2(1)(e) of the Prospectus Directive that are also (i) investment professionals falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005 (the "Order") or (ii) high net worth entities, and other persons to whom it may lawfully be communicated, falling within Article 49(2)(a) to (d) of the Order (each such person being referred to as a "relevant person"). This prospectus supplement and its contents are confidential and should not be distributed, published or reproduced (in whole or in part) or disclosed by recipients to any other person in the United Kingdom. Any person in the United Kingdom that is not a relevant persons should not act or rely on this document or any of its contents.

Notice to Prospective Investors in France

        Neither this prospectus supplement nor any other offering material relating to the ADSs described in this prospectus supplement has been submitted to the clearance procedures of the Autorité des Marchés Financiers or of the competent authority of another member state of the European Economic Area and notified to the Autorité des Marchés Financiers. The ADSs have not been offered or sold and will not be offered or sold, directly or indirectly, to the public in France. Neither this prospectus supplement nor any other offering material relating to the ADSs has been or will be:

        Such offers, sales and distributions will be made in France only:

        The ADSs may be resold directly or indirectly, only in compliance with articles L.411-1, L.411-2, L.412-1 and L.621-8 through L.621-8-3 of the French Code monétaire et financier.

Notice to Prospective Investors in Hong Kong

        The ADSs may not be offered or sold in Hong Kong by means of any document other than (i) in circumstances which do not constitute an offer to the public within the meaning of the Companies Ordinance (Cap. 32, Laws of Hong Kong), or (ii) to "professional investors" within the meaning of the Securities and Futures Ordinance (Cap. 571, Laws of Hong Kong) and any rules made thereunder, or (iii) in other circumstances which do not result in the document being a "prospectus" within the meaning of the Companies Ordinance (Cap. 32, Laws of Hong Kong) and no advertisement, invitation or document relating to the ADSs may be issued or may be in the possession of any person for the purpose of issue (in each case whether in Hong Kong or elsewhere), which is directed at, or the contents of which are likely to be accessed or read by, the public in Hong Kong (except if permitted to do so under the laws of Hong Kong) other than with respect to ADSs which are or are intended to be

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disposed of only to persons outside Hong Kong or only to "professional investors" within the meaning of the Securities and Futures Ordinance (Cap. 571, Laws of Hong Kong) and any rules made thereunder.

Notice to Prospective Investors in Japan

        The ADSs offered in this prospectus supplement have not been and will not be registered under the Financial Instruments and Exchange Law of Japan. ADSs have not been offered or sold and will not be offered or sold, directly or indirectly, in Japan or to or for the account of any resident of Japan (including any corporation or other entity organized under the laws of Japan), except (i) pursuant to an exemption from the registration requirements of the Financial Instruments and Exchange Law and (ii) in compliance with any other applicable requirements of Japanese law.

Notice to Prospective Investors in Singapore

        This prospectus supplement has not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this prospectus supplement and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of the ADSs may not be circulated or distributed, nor may the ADSs be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Singapore other than (i) to an institutional investor under Section 274 of the Securities and Futures Act, Chapter 289 of Singapore (the "SFA"), (ii) to a relevant person pursuant to Section 275(1), or any person pursuant to Section 275(1A), and in accordance with the conditions specified in Section 275 of the SFA or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA, in each case subject to compliance with conditions set forth in the SFA.

        Where the ADSs are subscribed or purchased under Section 275 of the SFA by a relevant person which is:

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LEGAL MATTERS

        Certain legal matters of United States federal law and New York State law will be passed upon for us by Mayer Brown LLP. The validity of the ordinary shares represented by ADSs and certain other matters as to English law will be passed upon for us by Mayer Brown International LLP. Covington & Burling LLP, New York, New York, is counsel to the underwriters in connection with this offering.

EXPERTS

        The consolidated financial statements of Adaptimmune Therapeutics plc as of December 31, 2016, December 31, 2015 and June 30, 2015, and for the year ended December 31, 2016, six month period ended December 31, 2015 and the years ended June 30, 2015 and June 30, 2014, have been incorporated by reference herein in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

        We have filed with the U.S. Securities and Exchange Commission a registration statement (including amendments and exhibits to the registration statement) on Form S-3 under the Securities Act. Our SEC filings are available to the public over the Internet at the SEC's website at http://www.sec.gov. Copies of certain information filed by us with the SEC are also available on our website at http://www.adaptimmune.com. Our website is not a part of this prospectus supplement and is not incorporated by reference in this prospectus supplement. You may also read and copy any document we file at the SEC's Public Reference Room, 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the operation of the Public Reference Room.

        This prospectus supplement is part of a registration statement we filed with the SEC. This prospectus supplement omits some information contained in the registration statement in accordance with SEC rules and regulations. You should review the information and exhibits in the registration statement for further information on us and our consolidated subsidiaries and the securities we are offering. Statements in this prospectus supplement concerning any document we filed as an exhibit to the registration statement or that we otherwise filed with the SEC are not intended to be comprehensive and are qualified by reference to these filings. You should review the complete document to evaluate these statements.

INCORPORATION BY REFERENCE

        The SEC allows us to incorporate by reference information into this document. This means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is an important part of this prospectus supplement, and information that we file later with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings made with the SEC under Sections 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act of 1934 made subsequent to the date of this prospectus supplement until the termination of the offering of the securities described in this prospectus supplement (other than information in such filings that was "furnished," under applicable SEC rules, rather than "filed").

        We incorporate by reference the following documents or information that we have filed with the SEC:

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        You may request a copy of these filings at no cost, by writing or telephoning us at the following address:

Adaptimmune Therapeutics plc
Attn: Company Secretary
101 Park Drive, Milton Park
Abingdon, Oxfordshire OX14 4RY
United Kingdom
(44) 1235 430000

        You should rely only on the information incorporated by reference or provided in this prospectus supplement. We have not authorized anyone else to provide you with different or additional information. An offer of these securities is not being made in any jurisdiction where the offer or sale is not permitted. You should not assume that the information in this prospectus supplement is accurate as of any date other than the date on the front of those documents.

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PROSPECTUS

$250,000,000

LOGO

American Depositary Shares representing Ordinary Shares



        We may offer, from time to time, the ADSs described in this prospectus, up to an aggregate amount of $250,000,000.

        This prospectus describes some of the general terms that may apply to the American Depositary Shares, or ADSs, of Adaptimmune Therapeutics plc. Each ADS represents 6 ordinary shares, par value £0.001 per share. The specific terms of the ADSs to be offered, and any other information relating to a specific offering, will be set forth in a supplement to this prospectus or in one or more documents incorporated by reference in this prospectus. You should carefully read this prospectus and the applicable prospectus supplement, as well as the documents incorporated or deemed to be incorporated by reference in this prospectus, before you purchase any of the ADSs offered hereby. This prospectus may not be used to sell these ADSs without a supplement.

        We may offer ADSs from time to time in amounts, at prices and on other terms to be determined at the time of offering. We may offer and sell ADSs to or through one or more underwriters, dealers and agents or directly to purchasers, on a continuous or delayed basis. The names of any underwriters, dealers or agents involved in the sale of any ADSs and the specific manner in which they may be offered, including any applicable purchase price, fee, commission or discount arrangement between or among them, will be set forth in the prospectus supplement covering the sale of those ADSs. See "Plan of Distribution."

        Our ADSs are listed on The Nasdaq Global Select Market under the symbol "ADAP." On September 6, 2016, the last reported sales price per ADS of our ADSs on The Nasdaq Global Select Market was $6.75.

        INVESTING IN OUR SECURITIES INVOLVES RISKS. SEE THE "RISK FACTORS" ON PAGE 6 OF THIS PROSPECTUS AND ANY SIMILAR SECTION CONTAINED IN THE APPLICABLE PROSPECTUS SUPPLEMENT OR ANY DOCUMENTS WE INCORPORATE BY REFERENCE CONCERNING FACTORS YOU SHOULD CONSIDER BEFORE INVESTING IN OUR SECURITIES.

        Neither the Securities and Exchange Commission nor any other regulatory body has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

   

The date of this prospectus is September 12, 2016.



TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

    1  

WHERE YOU CAN FIND MORE INFORMATION

    1  

INCORPORATION BY REFERENCE

    2  

THE COMPANY

    3  

FORWARD-LOOKING STATEMENTS

    4  

RISK FACTORS

    6  

USE OF PROCEEDS

    7  

DESCRIPTION OF SHARE CAPITAL

    8  

DESCRIPTION OF AMERICAN DEPOSITARY SHARES

    25  

PLAN OF DISTRIBUTION

    36  

LEGAL MATTERS

    38  

EXPERTS

    38  

SERVICE OF PROCESS AND ENFORCEMENT OF JUDGMENTS

    38  

i



ABOUT THIS PROSPECTUS

        This prospectus is part of a shelf registration statement that we filed with the Securities and Exchange Commission, which we refer to as the "SEC," utilizing a "shelf" registration process. Under this shelf registration process, we may, over time, offer and sell the securities described in this prospectus in one or more offerings, up to a total dollar amount of $250,000,000, as described in this prospectus. This prospectus provides you with a general description of the securities that may be offered. Each time we offer securities under this prospectus, we will provide a prospectus supplement or other offering materials that will contain specific information about the terms of that offering. We may also add, update or change information contained in this prospectus by means of a prospectus supplement or by incorporating by reference information that we file or furnish to the SEC. The registration statement that we filed with the SEC includes exhibits that provide more detail on the matters discussed in this prospectus. If the information in this prospectus is inconsistent with a prospectus supplement, you should rely on the information in that prospectus supplement. Please carefully read this prospectus and any prospectus supplement, together with the additional information described under the headings "Where You Can Find More Information" and "Incorporation by Reference," before purchasing any securities.

        You should rely only on the information contained or incorporated by reference in this prospectus, any prospectus supplement and any issuer free writing prospectus. "Incorporated by reference" means that we can disclose important information to you by referring you to another document filed separately with the SEC. We have not authorized any other person to provide you with different information. If anyone provides you with different information, you should not rely on it. We are not making an offer of these securities in any state or jurisdiction where the offer is not permitted. You should only assume that the information in this prospectus or in any prospectus supplement or issuer free writing prospectus is accurate only as of their respective dates. Our business, financial condition, results of operations and prospects may have changed since those dates.

        In this prospectus, "Adaptimmune," the "Group," the "Company," "we," "us" and "our" refer to Adaptimmune Therapeutics plc and its consolidated subsidiaries, except where the context otherwise requires. "Adaptimmune®" and "SPEAR®" are registered trademarks of Adaptimmune.


WHERE YOU CAN FIND MORE INFORMATION

        We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the Internet at the SEC's website located at http://www.sec.gov and on the investor relations pages of our website located at http://www.adaptimmune.com. You may also read and copy any document we file at the SEC's public reference room at 100 F Street, N.E., Washington, D.C. 20549. You can call the SEC at 1-800-SEC-0330 for further information on the public reference room.

        We will furnish to Citibank, N.A., as depositary bank of our ADSs, our annual reports. When the depositary bank receives these reports, it will upon our request promptly provide them to all holders of record of ADSs or otherwise make such reports available to such ADS holders in accordance with the terms of the deposit agreement. We will also furnish the depositary bank with all notices of shareholders' meetings and other reports and communications in English that we make available to our shareholders. The depositary bank will make these notices, reports and communications available to holders of ADSs and will upon our request mail to all holders of record of ADSs the information contained in any notice of a shareholders' meeting it receives.

        Information about us is also available on our website at http://www.adaptimmune.com. Such information on our website is not part of this prospectus.

1



INCORPORATION BY REFERENCE

        The SEC allows us to disclose certain information to you in this prospectus by referring you to documents previously filed with the SEC that include such information. The information incorporated by reference is an important part of this prospectus, and information that we file later with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings made with the SEC under Sections 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act of 1934 made subsequent to the date of this initial registration statement and prior to effectiveness of the registration statement and any reports filed by us with the SEC after the date of this prospectus until the termination of the offering of the securities described in this prospectus (other than information in such filings that was "furnished," under applicable SEC rules, rather than "filed").

        You may request a copy of these filings at no cost, by writing or telephoning us at the following address:

Adaptimmune Therapeutics plc
Attn: Company Secretary
101 Park Drive, Milton Park
Abingdon, Oxfordshire OX14 4RY
United Kingdom
(44) 1235 430000

        You should rely only on the information incorporated by reference or provided in this prospectus or any prospectus supplement. We have not authorized anyone else to provide you with different or additional information. An offer of these securities is not being made in any jurisdiction where the offer or sale is not permitted. You should not assume that the information in this prospectus or any prospectus supplement is accurate as of any date other than the date on the front of those documents.

2



THE COMPANY

        Adaptimmune is a clinical stage biopharmaceutical company focused on novel cancer immunotherapy products based on its SPEAR® (Specific Peptide Enhanced Affinity Receptor) T-cell platform. Established in 2008, the Company aims to utilize the body's own machinery—the T-cell—to target and destroy cancer cells by using engineered, increased affinity T-cell receptors, or TCRs, as a means of strengthening natural patient T-cell responses. Adaptimmune's lead program is a SPEAR T-cell therapy targeting the NY-ESO cancer antigen. Its NY-ESO SPEAR T-cell therapy has demonstrated signs of efficacy and tolerability in Phase 1/2 trials in solid tumors and in hematologic cancer types, including synovial sarcoma and multiple myeloma. Adaptimmune has a strategic collaboration and licensing agreement with GlaxoSmithKline, or GSK, for the development and commercialization of the NY-ESO TCR program. In addition, Adaptimmune has a number of proprietary programs. These include SPEAR T-cell therapies targeting the MAGE-A10 and alpha fetoprotein, or AFP, cancer antigens, which both have open Investigational New Drug Applications, or INDs, and a further SPEAR T-cell therapy targeting the MAGE-A4 cancer antigen which is in pre-clinical phase with IND acceptance targeted for 2017. The Company has identified over 30 intracellular target peptides preferentially expressed in cancer cells and is currently progressing 12 through unpartnered research programs. Adaptimmune has over 250 employees and is located in Oxfordshire, U.K. and Philadelphia, USA.

Corporate Information

        Our registered and principal executive offices are located at 101 Park Drive, Milton Park, Abingdon, Oxfordshire OX14 4RY, United Kingdom; our general telephone number is (44) 1235 430000; and our internet address is http://www.adaptimmune.com. Our website and the information contained on or accessible through our website are not part of this prospectus. Our agent for service of process in the United States is our subsidiary, Adaptimmune LLC, Two Commerce Square, Suite 1700, 2001 Market Street, Philadelphia, PA 19103. Since May 6, 2015, our ADSs, which each represent 6 ordinary shares, have been listed on The Nasdaq Global Select Market, or Nasdaq, under the symbol "ADAP."

3



FORWARD-LOOKING STATEMENTS

        This prospectus, the financial statements and other documents that we incorporate by reference in this prospectus and any related prospectus supplement may contain forward-looking statements that are based on our current expectations, assumptions, estimates and projections about us and our industry. All statements other than statements of historical fact in this prospectus, the financial statements and other documents that we incorporate by reference in this prospectus and any related prospectus supplement are forward-looking statements.

        These forward-looking statements are subject to known and unknown risks, uncertainties, assumptions and other factors that could cause our actual results of operations, financial condition, liquidity, performance, prospects, opportunities, achievements or industry results, as well as those of the markets we serve or intend to serve, to differ materially from those expressed in, or suggested by, these forward-looking statements. These forward-looking statements are based on assumptions regarding our present and future business strategies and the environment in which we expect to operate in the future. Important factors that could cause those differences include, but are not limited to:

4


        Additional factors that could cause actual results, financial condition, liquidity, performance, prospects, opportunities, achievements or industry results to differ materially include, but are not limited to, those discussed under "Risk Factors" in in Part II, Item 1A of our Quarterly Report on Form 10-Q for the period ended June 30, 2016, which is incorporated by reference herein, as updated by our other SEC filings filed after such Quarterly Report. Additional risks that we may currently deem immaterial or that are not presently known to us could also cause the forward-looking events discussed in this prospectus not to occur. Additional risks that we may currently deem immaterial or that are not presently known to us could also cause the forward-looking events discussed in this prospectus not to occur. The words "believe," "may," "will," "estimate," "continue," "anticipate," "intend," "expect" and similar words are intended to identify estimates and forward-looking statements. Estimates and forward-looking statements speak only at the date they were made, and we undertake no obligation to update or to review any estimate and/or forward-looking statement because of new information, future events or other factors. Estimates and forward-looking statements involve risks and uncertainties and are not guarantees of future performance. Our future results may differ materially from those expressed in these estimates and forward-looking statements. In light of the risks and uncertainties described above, the estimates and forward-looking statements discussed in this prospectus, the documents that we incorporate by reference in this prospectus and any related prospectus supplement might not occur, and our future results and our performance may differ materially from those expressed in such forward-looking statements due to, inclusive of, but not limited to, the factors mentioned above. Because of these uncertainties, you should not make any investment decision based on these estimates and forward-looking statements.

5



RISK FACTORS

        Our business, and an investment in the securities, is subject to uncertainties and risks. You should carefully consider and evaluate all of the information included and incorporated by reference in this prospectus, including the risk factors set forth below and the risk factors incorporated by reference from our most recent Quarterly Report on Form 10-Q for the period ended June 30, 2016, as updated by other SEC filings filed after such report, as well as any risks described in any applicable prospectus supplement. Our business, financial condition, results of operations and prospects could be materially adversely affected by any of these risks. The occurrence of any of these risks may cause you to lose all or part of your investment.

6



USE OF PROCEEDS

        We intend to use the net proceeds from the sale of the ADSs as set forth in the applicable prospectus supplement.

7



DESCRIPTION OF SHARE CAPITAL

        The following summary describes our share capital, the material provisions of our articles of association, and applicable provisions of the U.K. Companies Act 2006 (the "Companies Act 2006"). Because the following is only a summary, it does not contain all of the information that may be important to you. For a complete description, you should refer to our articles of association, a copy of which has been previously filed.

General

        We were incorporated pursuant to the laws of England and Wales as Adaptimmune Therapeutics Limited in December 2014 to become a holding company for Adaptimmune Limited. Pursuant to the terms of a corporate reorganization the first stage of which was completed on February 23, 2015, all of the issued share capital in Adaptimmune Limited was exchanged for identical shares in Adaptimmune Therapeutics Limited and, as a result, Adaptimmune Limited became a wholly owned subsidiary of Adaptimmune Therapeutics Limited. On March 20, 2015, all holders of options over ordinary shares of Adaptimmune Limited exchanged each of their options for equivalent options over ordinary shares of Adaptimmune Therapeutics Limited. On April 1, 2015, we re-registered Adaptimmune Therapeutics Limited as a public limited company and changed the company's name to Adaptimmune Therapeutics plc.

        We are registered with the Registrar of Companies in England and Wales under number 9338148 and our registered office is at 101 Park Drive, Milton Park, Oxfordshire OX14 4RY, United Kingdom.

        Following our corporate reorganization, certain resolutions were passed by our shareholders on April 27, 2015. These included resolutions for the adoption of new articles of association that became effective upon the admission of our ADSs to trading on Nasdaq on May 6, 2015, and which articles of association were amended by special resolution passed on June 16, 2016. See "—Key Provisions of Our Articles of Association."

        Certain other resolutions were passed by our shareholders at our first annual general meeting on December 17, 2015. These included resolutions for:

Issued Share Capital

        Our issued share capital as of August 31, 2016 was 424,711,900 ordinary shares with a par value of £0.001 per ordinary share. Each issued ordinary share is fully paid. We currently have no deferred shares in our issued share capital.

Ordinary Shares

        Our ordinary shares have the rights and restrictions described in "—Key Provisions of Our Articles of Association."

        As of August 31, 2016, there were options to purchase 48,456,517 ordinary shares outstanding. All options granted are exercisable at the share price on or around the date of the grant.

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        The vesting periods for options granted through August 31, 2016 are:

Options granted in 2009:

  100% on the third anniversary of the grant date

Options granted in 2011, 2012 2013 and April 2014:

  25% on the first anniversary and 75% in annual installments over the following three years

Options granted in December 2014:

  25% on the first anniversary and 75% in monthly installments over the following three years

Options granted in March 2015:

  25% on the first anniversary and 75% in monthly installments over the following three years

Options granted in May 2015:

  25% on the first anniversary and 75% in monthly installments over the following three years, except for options granted to Non-Executive Directors which all vested immediately

Options granted in January and April 2016:

  25% on the first anniversary and 75% in monthly installments over the following three years

Options granted in June 2016:

  25% on the first anniversary and 75% in monthly installments over the following two years

Options granted in August 2016

  25% on the first anniversary and 75% in monthly installments over the following three years, except for options granted to Non-Executive Directors which will all vest on the first anniversary of the grant date.

All options lapse after 10 years.

   

Preferred Shares

        Our board of directors may, from time to time, following an ordinary resolution of the ordinary shareholders granting authority to the directors to allot shares and special resolution of the ordinary shareholders to amend the articles of association (and disapply pre-emption rights, if not already disapplied), direct the issuance of preferred shares in series and may, at the time of issuance, determine the designations, powers, preferences, privileges, and relative participating, optional or special rights as well as the qualifications, limitations or restrictions thereof, including dividend rights, conversion rights, voting rights, terms of redemption and liquidation preferences, any or all of which may be greater than the rights of the ordinary shares. Holders of preferred shares may be entitled to receive a preference payment in the event of our liquidation before any payment is made to the holders of ordinary shares. There are currently no preferred shares outstanding, and we have no present intention to issue any preferred shares.

Key Provisions of Our Articles of Association

        The following is a summary of certain key provisions of our articles of association. Please note that this is only a summary and is not intended to be exhaustive. For further information please refer to the full version of our articles of association, which is included as an exhibit to the registration statement of which this prospectus is a part.

        All ordinary shares have the same rights and rank pari passu in all respects. Subject to the provisions of the Companies Act 2006 and any other relevant legislation, our shares may be issued with such preferred, deferred or other rights, or such restrictions, whether in relation to dividends, returns

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of capital, voting or otherwise, as we may determine by ordinary resolution (or, failing any such determination, as the directors may determine).

        Subject to any other provisions of our articles of association and without prejudice to any special rights, privileges or restrictions as to voting attached to any shares forming part of our share capital, the voting rights of shareholders are as follows. On a show of hands, each shareholder present in person, and each duly authorized representative present in person of a shareholder that is corporation, has one vote. On a show of hands, each proxy present in person who has been duly appointed by one or more shareholders has one vote, but a proxy has one vote for and one vote against a resolution if, in certain circumstances, the proxy is instructed by more than one shareholder to vote in different ways on a resolution. On a poll, each shareholder present in person or by proxy or (being a corporation) by a duly authorized representative has one vote for each share held by the shareholder.

        We are prohibited (to the extent specified by the Companies Act 2006) from exercising any rights to attend or vote at meetings in respect of any shares held by us as treasury shares.

        None of our shareholders (whether present in person by proxy or, in the case of a corporate member, by a duly authorized representative) shall (unless the directors otherwise determine) be entitled to vote at any general meeting or at any separate class meeting in respect of any share held by him unless all calls or other sums payable by him in respect of that share have been paid.

        The directors may from time to time make calls on shareholders in respect of any moneys unpaid on their shares, whether in respect of the nominal value of the shares or by way of premium. Shareholders are required to pay called amounts on shares subject to receiving at least 14 clear days' notice specifying the time and place for payment. If a shareholder fails to pay any part of a call, the directors may serve further notice naming another day not being less than 14 clear days from the date of the further notice requiring payment and stating that in the event of non-payment the shares in respect of which the call was made will be liable to be forfeited. Subsequent forfeiture requires a resolution by the directors.

        Subject to the Companies Act 2006 and the provisions of all other relevant legislation, we may by ordinary resolution declare dividends in accordance with the respective rights of shareholders but no such dividend shall exceed the amount recommended by the directors. If, in the opinion of the directors, our profits available for distribution justify such payments, the directors may pay fixed dividends payable on any of our shares with preferential rights, half-yearly or otherwise, on fixed dates and from time to time pay interim dividends to the holders of any class of shares. Subject to any special rights attaching to or terms of issue of any shares, all dividends shall be declared and paid according to the amounts paid up on the shares on which the dividend is paid. No dividend shall be payable to us in respect of any shares held by us as treasury shares (except to the extent permitted by the Companies Act 2006 and any other relevant legislation).

        We may, upon the recommendation of the directors, by ordinary resolution, direct payment of a dividend wholly or partly by the distribution of specific assets.

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        All dividends unclaimed may be invested or otherwise used at the directors' discretion for our benefit until claimed (subject as provided in the articles of association), and all dividends unclaimed after a period of 12 years from the date when such dividend became due for payment shall be forfeited and shall revert to us.

        The directors may, if so authorized by ordinary resolution passed at any general meeting, offer any holders of the ordinary shares the right to elect to receive in lieu of that dividend an allotment of ordinary shares credited as fully paid.

        We may cease to send any check or warrant by mail or may stop the transfer of any sum by any bank or other funds transfer system for any dividend payable on any of our shares, which is normally paid in that manner on those shares if in respect of at least two consecutive dividends the checks or warrants have been returned undelivered or remain uncashed or the transfer has failed and reasonable inquiries made by us have failed to establish any new address of the holder.

        We or the directors may specify a "record date" on which persons registered as the holders of shares shall be entitled to receipt of any dividend.

        Subject to any special rights attaching to or the terms of issue of any shares, on any winding-up of the Company our surplus assets remaining after satisfaction of our liabilities will be distributed among our shareholders in proportion to their respective holdings of shares and the amounts paid up on those shares.

        On any winding-up of the Company (whether the liquidation is voluntary, under supervision or by the Court, the liquidator may with the authority of a special resolution of the Company and any other sanction required by any relevant legislation, divide among our shareholders (excluding the Company itself to the extent that it is a shareholder by virtue of its holding any shares or treasury shares) in specie or in kind the whole or any part of our assets (subject to any special rights attached to any shares issued by us in the future) and may for that purpose set such value as he deems fair upon any one or more class or classes of property and may determine how that division shall be carried out as between the shareholders or different classes of shareholders. The liquidator may, with that sanction, vest the whole or any part of the assets in trustees upon such trusts for the benefit of the shareholders as he with the relevant authority determines, and the liquidation of the Company may be closed and the Company dissolved, but so that no shareholders shall be compelled to accept any shares or other property in respect of which there is a liability.

        The rights or privileges attached to any class of shares may (unless otherwise provided by the terms of the issue of the shares of that class) be varied or abrogated with the consent in writing of the holders of three-fourths in requisite amount of the issued shares of that class (excluding any shares of that class held as treasury shares) or with the sanction of a special resolution passed at a separate general meeting of the shareholders of that class, but not otherwise.

        All of our shares are in registered form and may be transferred by a transfer in any usual or common form or any form acceptable to the directors and permitted by the Companies Act 2006 and any other relevant legislation.

        The directors may decline to register a transfer of a share that is:

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        We may, by ordinary resolution, consolidate and divide all or any of our share capital into shares of a larger nominal amount than our existing shares or sub-divide our shares, or any of them, into shares of a smaller amount than our existing shares. Subject to the provisions of the Companies Act 2006 and any other relevant legislation, we may by special resolution reduce our share capital, any capital redemption reserve fund or any share premium account and may redeem or purchase any of our own shares.

        There are no rights of pre-emption under our articles of association in respect of transfers of issued ordinary shares. In certain circumstances, our shareholders may have statutory pre-emption rights under the Companies Act 2006 in respect of the allotment of new shares in the Company. These statutory pre-emption rights, when applicable, would require us to offer new shares for allotment to existing shareholders on a pro rata basis before allotting them to other persons. In such circumstances, the procedure for the exercise of such statutory pre-emption rights would be set out in the documentation by which such ordinary shares would be offered to our shareholders. These statutory pre-emption rights may be disapplied by a special resolution passed by shareholders in a general meeting in accordance with the provisions of the Companies Act 2006.

        Unless and until we in a general meeting of our shareholders otherwise determine, the number of directors shall not be subject to any maximum but shall not be less than two.

        Under our directors' general power to manage our business, our directors may exercise all the powers of the Company to borrow money and to mortgage or charge our undertaking, property and uncalled capital or parts thereof and to issue debentures and other securities, whether outright or as collateral security for any debt, liability or obligation of the Company or of any third party.

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        The directors may exercise all the powers of the Company to provide benefits, either by the payment of gratuities or pensions or by insurance or in any other manner whether similar to the foregoing or not, for any director or former director, or any person who is or was at any time employed by, or held an executive or other office or place of profit in, the Company or any body corporate that is or has been a subsidiary of the Company or a predecessor of the business of the Company or of any such subsidiary and for the families and persons who are or was a dependent of any such persons and for the purpose of providing any such benefits contribute to any scheme trust or fund or pay any premiums.

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        The directors may resolve to change the Company's name.

        Subject to the provisions of any relevant legislation, each of our directors and other officers (excluding an auditor) are entitled to be indemnified by us against all liabilities incurred by him in the execution and discharge of his duties or in relation to those duties. The Companies Act 2006 renders

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void an indemnity for a director against any liability attaching to him in connection with any negligence, default, breach of duty or breach of trust in relation to the company of which he is a directors as described in"—Differences in Corporate Law—Liability of Directors and Officers."

        We shall in each year hold a general meeting of our shareholders in addition to any other meetings in that year, and shall specify the meeting as such in the notice convening it. The annual general meeting shall be held at such time and place as the directors may appoint.

        The directors may call a general meeting of shareholders. The directors must call a general meeting if the shareholders and the Companies Act 2006 require them to do so. The arrangements for the calling of general meetings are described in "—Differences in Corporate Law—Notice of General Meetings."

        No business shall be transacted at any general meeting unless a quorum is present when the meeting proceeds to business but the absence of a quorum shall not preclude the appointment of a chairman that shall not be treated as part of the business of a meeting. One or more qualifying persons present at a meeting and between them holding (or being the proxy or corporate representative of the holders of) at least one-third in number of the issued shares (excluding any shares held as treasury shares) entitled to vote on the business to be transacted are a quorum. A qualifying person for these purposes is an individual who is a member, a person authorized to act as the representative of a member (being a corporation) in relation to the meeting or a person appointed as proxy of a member in relation to the meeting.

        Pursuant to sections 979 to 991 of the Companies Act 2006, where a takeover offer has been made for the Company and the offeror has acquired or unconditionally contracted to acquire not less than 90 percent of the voting rights carried by those shares, the offeror may give notice, to the holder of any shares to which the offer relates which the offeror has not acquired or unconditionally contracted to acquire that he wishes to acquire and is entitled to so acquire, to acquire those shares of the same terms as the general offer.

        Pursuant to Part 22 of the Companies Act 2006 and our articles of association, we are empowered by notice in writing to require any person whom we know to be, or have reasonable cause to believe to be, interested in the Company, our shares or, at any time during the three years immediately preceding the date on which the notice is issued has been so interested, within a reasonable time to disclose to us particulars of any interest, rights, agreements or arrangements affecting any of the shares held by that person or in which such other person as aforesaid is interested (so far as is within his knowledge).

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        Under our articles of association, if a person defaults in supplying us with the required particulars in relation to the shares in question ("default shares"), the directors may be notice direct that:

        Under English law, a public limited company may only purchase its own shares out of the distributable profits of the company or the proceeds of a fresh issue of shares made for the purpose of financing the purchase. A limited company may not purchase its own shares if as a result of the purchase there would no longer be any issued shares of the company other than redeemable shares or shares held as treasury shares.

        Subject to the above, we may purchase our own shares in the manner prescribed below. We may purchase on a recognized investment exchange our own fully paid shares pursuant to an ordinary resolution of the Company. The resolution authorizing the purchase must:

        We may purchase our own fully paid shares otherwise than on a recognized investment exchange pursuant to a purchase contract authorized by special resolution of the Company before the purchase takes place. Any authority will not be effective if any shareholder from whom we propose to purchase shares votes on the resolution and the resolution would not have been passed if he had not done so. The resolution authorizing the purchase must specify a date, not being later than five years after the passing of the resolution, on which the authority to purchase is to expire.

Registration Rights

        Under the Investors' Rights Agreement, dated February 23, 2015, or the Investors' Rights Agreement, certain of our shareholders have registration rights for the resale of the ordinary shares held by them. Under this agreement, the holders of approximately 84,948,400 ordinary shares (including in the form of ADSs) have the right to require us to register the offer and sale of their ordinary shares, or the registrable securities (including in the form of ADSs), or to include such registrable securities in registration statements we file, in each case as described below.

        At any time after six months following our IPO, the holders of more than fifty percent of the registrable securities than outstanding have the right to demand that we use our best efforts to file a registration statement, provided that the anticipated aggregated offering price for such offering must exceed $10 million. We are only obligated to file up to two registration statements in connection with the exercise of demand registration rights.

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        In addition, at any time after we qualify to file a registration statement on Form F-3 (or any substantially similar form such as Form S-3), any holder of registrable securities has the right to demand that we use our commercially reasonable efforts to file a registration statement on Form F-3 (or any substantially similar form such as Form S-3) covering at least $5 million of registrable securities. We are not obligated to file more than two such registration statements in any 12-month period.

        If we propose to register (other than in certain excluded registrations) any ordinary shares or ADSs representing such ordinary shares, shareholders who have entered into the Investors' Rights Agreement are entitled to notice of such registration and to include their registrable securities in that registration. The registration of such shareholders' registrable securities pursuant to a company registration does not relieve us of the obligation to effect a demand registration. The managing underwriter has the right to limit the number of registrable securities included in a company registration if the managing underwriter believes it would interfere with the successful marketing of the ordinary shares or ADSs.

        Subject to limited exceptions, the Investors' Rights Agreement provides that we must pay all registration expenses in connection with the registration rights set forth above. The Investors' Rights Agreement contains customary indemnification and contribution provisions.

        The registration rights set forth above terminate upon the earlier of (1) sale of the company (2) as to a particular holder, when such holder can sell all of its ordinary shares (including in the form of ADSs) without limitation during a three-month period without registration pursuant to Rule 144 under the Securities Act or another exemption; or (3) the fifth anniversary of the completion of our IPO.

Differences in Corporate Law

        The applicable provisions of the Companies Act 2006 differ from laws applicable to U.S. corporations and their shareholders. Set forth below is a summary of certain differences between the provisions of the Companies Act 2006 applicable to us and the Delaware General Corporation Law relating to shareholders' rights and protections. This summary is not intended to be a complete discussion of the respective rights and it is qualified in its entirety by reference to Delaware law and English law.

 
  England and Wales   Delaware

Number of Directors

  Under the Companies Act 2006, a public limited company must have at least two directors and the number of directors may be fixed by or in the manner provided in a company's articles of association.   Under Delaware law, a corporation must have at least one director and the number of directors shall be fixed by or in the manner provided in the bylaws.

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  England and Wales   Delaware

Removal of Directors

 

Under the Companies Act 2006, shareholders may remove a director without cause by an ordinary resolution (which is passed by a simple majority of those voting in person or by proxy at a general meeting) irrespective of any provisions of any service contract the director has with the company, provided that 28 clear days' notice of the resolution is given to the company and its shareholders and certain other procedural requirements under the Companies Act 2006 are followed (such as allowing the director to make representations against his or her removal either at the meeting or in writing).

 

Under Delaware law, unless otherwise provided in the certificate of incorporation, directors may be removed from office, with or without cause, by a majority stockholder vote, though in the case of a corporation whose board is classified, stockholders may effect such removal only for cause.

Vacancies on the Board of Directors

 

Under English law, the procedure by which directors (other than a company's initial directors) are appointed is generally set out in a company's articles of association, provided that where two or more persons are appointed as directors of a public limited company by resolution of the shareholders, resolutions appointing each director must be voted on individually.

 

Under Delaware law, vacancies on a corporation's board of directors, including those caused by an increase in the number of directors, may be filled by a majority of the remaining directors.

Annual General Meeting

 

Under the Companies Act 2006, a public limited company must hold an annual general meeting in each six-month period following the company's annual accounting reference date.

 

Under Delaware law, the annual meeting of stockholders shall be held at such place, on such date and at such time as may be designated from time to time by the board of directors or as provided in the certificate of incorporation or by the bylaws.

General Meeting

 

Under the Companies Act 2006, a general meeting of the shareholders of a public limited company may be called by the directors.

Shareholders holding at least 5% of the paid-up capital of the company carrying voting rights at general meetings can require the directors to call a general meeting.

 

Under Delaware law, special meetings of the stockholders may be called by the board of directors or by such person or persons as may be authorized by the certificate of incorporation or by the bylaws.

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  England and Wales   Delaware

Notice of General Meetings

 

Under the Companies Act 2006, 21 clear days' notice must be given for an annual general meeting and any resolutions to be proposed at the meeting. Subject to a company's articles of association providing for a longer period, at least 14 clear days' notice is required for any other general meeting. In addition, certain matters (such as the removal of directors or auditors) require special notice, which is 28 clear days' notice. The shareholders of a company may in all cases consent to a shorter notice period, the proportion of shareholders' consent required being 100% of those entitled to attend and vote in the case of an annual general meeting and, in the case of any other general meeting, a majority in number of the members having a right to attend and vote at the meeting, being a majority who together hold not less than 95% in nominal value of the shares giving a right to attend and vote at the meeting.

 

Under Delaware law, unless otherwise provided in the certificate of incorporation or bylaws, written notice of any meeting of the stockholders must be given to each stockholder entitled to vote at the meeting not less than 10 nor more than 60 days before the date of the meeting and shall specify the place, date, hour, and purpose or purposes of the meeting.

Proxy

 

Under the Companies Act 2006, at any meeting of shareholders, a shareholder may designate another person to attend, speak and vote at the meeting on their behalf by proxy.

 

Under Delaware law, at any meeting of stockholders, a stockholder may designate another person to act for such stockholder by proxy, but no such proxy shall be voted or acted upon after three years from its date, unless the proxy provides for a longer period.

Preemptive Rights

 

Under the Companies Act 2006, "equity securities" (being (i) shares in the company other than shares that, with respect to dividends and capital, carry a right to participate only up to a specified amount in a distribution ("ordinary shares") or (ii) rights to subscribe for, or to convert securities into, ordinary shares) proposed to be allotted for cash must be offered first to the existing equity shareholders in the company in proportion to the respective nominal value of their holdings, unless an exception applies or a special resolution to the contrary has been passed by shareholders in a general meeting or the articles of association provide otherwise in each case in accordance with the provisions of the Companies Act 2006.

 

Under Delaware law, unless otherwise provided in a corporation's certificate of incorporation, a stockholder does not, by operation of law, possess preemptive rights to subscribe to additional issuances of the corporation's stock.

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  England and Wales   Delaware

Liability of Directors and Officers

 

Under the Companies Act 2006, any provision (whether contained in a company's articles of association or any contract or otherwise) that purports to exempt a director of a company (to any extent) from any liability that would otherwise attach to him in connection with any negligence, default, breach of duty or breach of trust in relation to the company is void.

Any provision by which a company directly or indirectly provides an indemnity (to any extent) for a director of the company or of an associated company against any liability attaching to him in connection with any negligence, default, breach of duty or breach of trust in relation to the company of which he is a director is also void except as permitted by the Companies Act 2006, which provides exceptions for the company to (a) purchase and maintain insurance against such liability; (b) provide a "qualifying third party indemnity" (being an indemnity against liability incurred by the director to a person other than the company or an associated company as long as he is successful in defending the claim or criminal proceedings); and (c) provide a "qualifying pension scheme indemnity" (being an indemnity against liability incurred in connection with the company's activities as trustee of an occupational pension plan).

  Under Delaware law, a corporation's certificate of incorporation may include a provision eliminating or limiting the personal liability of a director to the corporation and its stockholders for damages arising from a breach of fiduciary duty as a director. However, no provision can limit the liability of a director for:

any breach of the director's duty of loyalty to the corporation or its stockholders;

acts or omissions not in good faith or that involve intentional misconduct or a knowing violation of law;

intentional or negligent payment of unlawful dividends or stock purchases or redemptions; or

any transaction from which the director derives an improper personal benefit.

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  England and Wales   Delaware

Voting Rights

 

Under English law, unless a poll is demanded by the shareholders of a company or is required by the chairman of the meeting or the company's articles of association, shareholders shall vote on all resolutions on a show of hands. Under the Companies Act 2006, a poll may be demanded by (a) not fewer than five shareholders having the right to vote on the resolution; (b) any shareholder(s) representing at least 10% of the total voting rights of all the shareholders having the right to vote on the resolution; or (c) any shareholder(s) holding shares in the company conferring a right to vote on the resolution being shares on which an aggregate sum has been paid up equal to not less than 10% of the total sum paid up on all the shares conferring that right. A company's articles of association may provide more extensive rights for shareholders to call a poll.

 

Delaware law provides that, unless otherwise provided in the certificate of incorporation, each stockholder is entitled to one vote for each share of capital stock held by such stockholder.

 

Under English law, an ordinary resolution is passed on a show of hands if it is approved by a simple majority (more than 50%) of the votes cast by shareholders present (in person or by proxy) and entitled to vote. If a poll is demanded, an ordinary resolution is passed if it is approved by holders representing a simple majority of the total voting rights of shareholders present (in person or by proxy) who (being entitled to vote) vote on the resolution. Special resolutions require the affirmative vote of not less than 75% of the votes cast by shareholders present (in person or by proxy) at the meeting.

   

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  England and Wales   Delaware

Shareholder Vote on Certain Transactions

  The Companies Act 2006 provides for schemes of arrangement, which are arrangements or compromises between a company and any class of shareholders or creditors and used in certain types of reconstructions, amalgamations, capital reorganizations or takeovers. These arrangements require:

the approval at a shareholders' or creditors' meeting convened by order of the court, of a majority in number of shareholders or creditors representing 75% in value of the capital held by, or debt owed to, the class of shareholders or creditors, or class thereof present and voting, either in person or by proxy; and

the approval of the court.

  Generally, under Delaware law, unless the certificate of incorporation provides for the vote of a larger portion of the stock, completion of a merger, consolidation, sale, lease or exchange of all or substantially all of a corporation's assets or dissolution requires:

the approval of the board of directors; and

approval by the vote of the holders of a majority of the outstanding stock or, if the certificate of incorporation provides for more or less than one vote per share, a majority of the votes of the outstanding stock of a corporation entitled to vote on the matter.

Standard of Conduct for Directors

  Under English law, a director owes various statutory and fiduciary duties to the company, including:

to act in the way he considers, in good faith, would be most likely to promote the success of the company for the benefit of its members as a whole;

to avoid a situation in which he has, or can have, a direct or indirect interest that conflicts, or possibly conflicts, with the interests of the company;

to act in accordance with the company's constitution and only exercise his powers for the purposes for which they are conferred;

to exercise independent judgment;

to exercise reasonable care, skill and diligence;

not to accept benefits from a third party conferred by reason of his being a director or doing (or not doing) anything as a director; and

a duty to declare any interest that he has, whether directly or indirectly, in a proposed or existing transaction or arrangement with the company.

 

Delaware law does not contain specific provisions setting forth the standard of conduct of a director. The scope of the fiduciary duties of directors is generally determined by the courts of the State of Delaware. In general, directors have a duty to act without self-interest, on a well-informed basis and in a manner they reasonably believe to be in the best interest of the stockholders.

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  England and Wales   Delaware

Stockholder Suits

 

Under English law, generally, the company, rather than its shareholders, is the proper claimant in an action in respect of a wrong done to the company or where there is an irregularity in the company's internal management. Notwithstanding this general position, the Companies Act 2006 provides that (i) a court may allow a shareholder to bring a derivative claim (that is, an action in respect of and on behalf of the company) in respect of a cause of action arising from a director's negligence, default, breach of duty or breach of trust and (ii) a shareholder may bring a claim for a court order where the company's affairs have been or are being conducted in a manner that is unfairly prejudicial to some of its shareholders.

  Under Delaware law, a stockholder may initiate a derivative action to enforce a right of a corporation if the corporation fails to enforce the right itself. The complaint must:

state that the plaintiff was a stockholder at the time of the transaction of which the plaintiff complains or that the plaintiffs shares thereafter devolved on the plaintiff by operation of law; and

allege with particularity the efforts made by the plaintiff to obtain the action the plaintiff desires from the directors and the reasons for the plaintiff's failure to obtain the action; or

state the reasons for not making the effort.

Additionally, the plaintiff must remain a stockholder through the duration of the derivative suit. The action will not be dismissed or compromised without the approval of the Delaware Court of Chancery.

        If at the time of a takeover offer the U.K. Panel on Takeovers and Mergers (the "Takeover Panel") determines that we have our place of central management and control in the United Kingdom, we would be subject to the U.K. City Code on Takeovers and Mergers (the "Takeover Code"), which is issued and administered by the Takeover Panel. The Takeover Code provides a framework within which takeovers of companies subject to it are conducted. In particular, the Takeover Code contains certain rules in respect of mandatory offers. Under Rule 9 of the Takeover Code, if a person:

the acquirer and, depending on the circumstances, its concert parties, would be required (except with the consent of the Takeover Panel) to make a cash offer for our outstanding shares at a price not less than the highest price paid for any interests in the shares by the acquirer or its concert parties during the previous 12 months.

        There are no governmental laws, decrees, regulations or other legislation in the United Kingdom that may affect the import or export of capital, including the availability of cash and cash equivalents for use by us, or that may affect the remittance of dividends, interest, or other payments by us to non-resident holders of our ordinary shares or ordinary shares, other than withholding tax requirements. There is no limitation imposed by English law or our articles of association on the right of non-residents to hold or vote shares.

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DESCRIPTION OF AMERICAN DEPOSITARY SHARES

        Citibank, N.A. has agreed to act as the depositary bank for the American Depositary Shares. Citibank's depositary offices are located at 388 Greenwich Street, New York, New York 10013. American Depositary Shares are frequently referred to as "ADSs" and represent ownership interests in securities that are on deposit with the depositary bank. ADSs may be represented by certificates that are commonly known as "American Depositary Receipts" or "ADRs." The depositary bank typically appoints a custodian to safekeep the securities on deposit. In this case, the custodian is Citibank, N.A. London Branch, having its principal office at Citigroup Centre, Canada Square, Canary Wharf, London E14 5LB, England.

        We have appointed Citibank as depositary bank pursuant to a deposit agreement. A copy of the deposit agreement is on file with the SEC under cover of a Registration Statement on Form F-6. You may obtain a copy of the deposit agreement from the SEC's Public Reference Room at 100 F Street, N.E., Washington, D.C. 20549 and from the SEC's website (www.sec.gov). Please refer to Registration Number 333-203642 when retrieving such copy.

        We are providing you with a summary description of the material terms of the ADSs and of your material rights as an owner of ADSs. Please remember that summaries by their nature lack the precision of the information summarized and that the rights and obligations of an owner of ADSs will be determined by reference to the terms of the deposit agreement and not by this summary. We urge you to review the deposit agreement in its entirety. The portions of this summary description that are italicized describe matters that may be relevant to the ownership of ADSs but that may not be contained in the deposit agreement.

        Each ADS represents the right to receive and to exercise the beneficial ownership interests in 6 ordinary shares that are on deposit with the depositary bank and/or custodian. An ADS also represents the right to receive, and to exercise the beneficial interests in any other property received by the depositary bank or the custodian on behalf of the owner of the ADS but that has not been distributed to the owners of ADSs because of legal restrictions or practical considerations. The custodian, the depositary bank and their respective nominees will hold all deposited property for the benefit of the holders and beneficial owners of ADSs. The deposited property does not constitute the proprietary assets of the depositary bank, the custodian or their nominees. Beneficial ownership in the deposited property will under the terms of the deposit agreement be vested in the beneficial owners of the ADSs. The depositary bank, the custodian and their respective nominees will be the record holders of the deposited property represented by the ADSs for the benefit of the holders and beneficial owners of the corresponding ADSs. A beneficial owner of ADSs may or may not be the holder of ADSs. Beneficial owners of ADSs will be able to receive, and to exercise beneficial ownership interests in the deposited property only through the registered holders of the ADSs, the registered holders of the ADSs (on behalf of the applicable ADS owners) only through the depositary bank, and the depositary bank (on behalf of the owners of the corresponding ADSs) directly, or indirectly through the custodian or their respective nominees, in each case upon the terms of the deposit agreement.

        If you become an owner of ADSs, you will become a party to the deposit agreement and therefore will be bound to its terms and to the terms of any ADR that represents your ADSs. The deposit agreement and the ADR specify our rights and obligations as well as your rights and obligations as an owner of ADSs and those of the depositary bank. As an ADS holder you appoint the depositary bank to act on your behalf in certain circumstances. The deposit agreement and the ADRs are governed by New York law. However, our obligations to the holders of ordinary shares will continue to be governed by the laws of England and Wales, which may be different from the laws in the United States.

        In addition, applicable laws and regulations may require you to satisfy reporting requirements and obtain regulatory approvals in certain circumstances. You are solely responsible for complying with such reporting requirements and obtaining such approvals. Neither the depositary bank, the custodian, us or

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any of their or our respective agents or affiliates shall be required to take any actions whatsoever on your behalf to satisfy such reporting requirements or obtain such regulatory approvals under applicable laws and regulations.

        As an owner of ADSs, we will not treat you as one of our shareholders and you will not have direct shareholder rights. The depositary bank will hold on your behalf the shareholder rights attached to the ordinary shares underlying your ADSs. As an owner of ADSs you will be able to exercise the shareholders rights for the ordinary shares represented by your ADSs through the depositary bank only to the extent contemplated in the deposit agreement. To exercise any shareholder rights not contemplated in the deposit agreement you will, as an ADS owner, need to arrange for the cancellation of your ADSs and become a direct shareholder.

        As an owner of ADSs, you may hold your ADSs either by means of an ADR registered in your name, through a brokerage or safekeeping account, or through an account established by the depositary bank in your name reflecting the registration of uncertificated ADSs directly on the books of the depositary bank (commonly referred to as the "direct registration system" or "DRS"). The direct registration system reflects the uncertificated (book-entry) registration of ownership of ADSs by the depositary bank. Under the direct registration system, ownership of ADSs is evidenced by periodic statements issued by the depositary bank to the holders of the ADSs. The direct registration system includes automated transfers between the depositary bank and The Depository Trust Company ("DTC"), the central book-entry clearing and settlement system for equity securities in the United States. If you decide to hold your ADSs through your brokerage or safekeeping account, you must rely on the procedures of your broker or bank to assert your rights as ADS owner. Banks and brokers typically hold securities such as the ADSs through clearing and settlement systems such as DTC. The procedures of such clearing and settlement systems may limit your ability to exercise your rights as an owner of ADSs. Please consult with your broker or bank if you have any questions concerning these limitations and procedures. All ADSs held through DTC will be registered in the name of a nominee of DTC. This summary description assumes you have opted to own the ADSs directly by means of an ADS registered in your name and, as such, we will refer to you as the "holder." When we refer to "you," we assume the reader owns ADSs and will own ADSs at the relevant time.

        The registration of the ordinary shares in the name of the depositary bank or the custodian shall, to the maximum extent permitted by applicable law, vest in the depositary bank or the custodian the record ownership in the applicable ordinary shares with the beneficial ownership rights and interests in such ordinary shares being at all times vested with the beneficial owners of the ADSs representing the ordinary shares. The depositary bank or the custodian shall at all times be entitled to exercise the beneficial ownership rights in all deposited property, in each case only on behalf of the holders and beneficial owners of the ADSs representing the deposited property.

Dividends and Distributions

        As a holder of ADSs, you generally have the right to receive the distributions we make on the securities deposited with the custodian. Your receipt of these distributions may be limited, however, by practical considerations and legal limitations. Holders of ADSs will receive such distributions under the terms of the deposit agreement in proportion to the number of ADSs held as of the specified record date, after deduction of the applicable fees, taxes and expenses.

        Whenever we make a cash distribution for the securities on deposit with the custodian, we will deposit the funds with the custodian. Upon receipt of confirmation of the deposit of the requisite funds, the depositary bank will arrange for the funds to be converted into U.S. dollars and for the

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distribution of the U.S. dollars to the holders, subject to the laws and regulations of England and Wales.

        The conversion into U.S. dollars will take place only if practicable and if the U.S. dollars are transferable to the United States. The depositary bank will apply the same method for distributing the proceeds of the sale of any property (such as undistributed rights) held by the custodian in respect of securities on deposit.

        The distribution of cash will be made net of the fees, expenses, taxes and governmental charges payable by holders under the terms of the deposit agreement. The depositary bank will hold any cash amounts it is unable to distribute in a non-interest bearing account for the benefit of the applicable holders and beneficial owners of ADSs until the distribution can be effected or the funds that the depositary bank holds must be escheated as unclaimed property in accordance with the laws of the relevant states of the United States.

        Whenever we make a free distribution of ordinary shares for the securities on deposit with the custodian, we will deposit the applicable number of ordinary shares with the custodian. Upon receipt of confirmation of such deposit, the depositary bank will either distribute to holders new ADSs representing the ordinary shares deposited or modify the ADS-to-ordinary share ratio, in which case each ADS you hold will represent rights and interests in the additional ordinary shares so deposited. Only whole new ADSs will be distributed. Fractional entitlements will be sold and the proceeds of such sale will be distributed as in the case of a cash distribution.

        The distribution of new ADSs or the modification of the ADS-to-ordinary share ratio upon a distribution of ordinary shares will be made net of the fees, expenses, taxes and governmental charges payable by holders under the terms of the deposit agreement. In order to pay such taxes or governmental charges, the depositary bank may sell all or a portion of the new ordinary shares so distributed.

        No such distribution of new ADSs will be made if it would violate a law (i.e., the U.S. securities laws) or if it is not operationally practicable. If the depositary bank does not distribute new ADSs as described above, it may sell the ordinary shares received upon the terms described in the deposit agreement and will distribute the proceeds of the sale as in the case of a distribution of cash.

        Whenever we intend to distribute rights to purchase additional ordinary shares, we will give prior notice to the depositary bank and we will assist the depositary bank in determining whether it is lawful and reasonably practicable to distribute rights to purchase additional ADSs to holders.

        The depositary bank will establish procedures to distribute rights to purchase additional ADSs to holders and to enable such holders to exercise such rights if it is lawful and reasonably practicable to make the rights available to holders of ADSs, and if we provide all of the documentation contemplated in the deposit agreement (such as opinions to address the lawfulness of the transaction). You may have to pay fees, expenses, taxes and other governmental charges to subscribe for the new ADSs upon the exercise of your rights. The depositary bank is not obligated to establish procedures to facilitate the distribution and exercise by holders of rights to purchase new ordinary shares other than in the form of ADSs.

        The depositary bank will not distribute the rights to you if:

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        The depositary bank will sell the rights that are not exercised or not distributed if such sale is lawful and reasonably practicable. The proceeds of such sale will be distributed to holders as in the case of a cash distribution. If the depositary bank is unable to sell the rights, it will allow the rights to lapse.

        Whenever we intend to distribute a dividend payable at the election of shareholders either in cash or in additional shares, we will give prior notice thereof to the depositary bank and will indicate whether we wish the elective distribution to be made available to you. In such case, we will assist the depositary bank in determining whether such distribution is lawful and reasonably practicable.

        The depositary bank will make the election available to you only if it is reasonably practicable and if we have provided all of the documentation contemplated in the deposit agreement. In such case, the depositary bank will establish procedures to enable you to elect to receive either cash or additional ADSs, in each case as described in the deposit agreement.

        If the election is not made available to you, you will receive either cash or additional ADSs, depending on what a shareholder in England and Wales would receive upon failing to make an election, as more fully described in the deposit agreement.

        Whenever we intend to distribute property other than cash, ordinary shares or rights to purchase additional ordinary shares, we will notify the depositary bank in advance and will indicate whether we wish such distribution to be made to you. If so, we will assist the depositary bank in determining whether such distribution to holders is lawful and reasonably practicable.

        If it is reasonably practicable to distribute such property to you and if we provide all of the documentation contemplated in the deposit agreement, the depositary bank will distribute the property to the holders in a manner it deems practicable.

        The distribution will be made net of fees, expenses, taxes and governmental charges payable by holders under the terms of the deposit agreement. In order to pay such taxes and governmental charges, the depositary bank may sell all or a portion of the property received.

        The depositary bank will not distribute the property to you and will sell the property if:

        The proceeds of such a sale will be distributed to holders as in the case of a cash distribution.

        Whenever we decide to redeem any of the securities on deposit with the custodian, we will notify the depositary bank in advance. If it is practicable and if we provide all of the documentation contemplated in the deposit agreement, the depositary bank will provide notice of the redemption to the holders.

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        The custodian will be instructed to surrender the shares being redeemed against payment of the applicable redemption price. The depositary bank will convert the redemption funds received into U.S. dollars upon the terms of the deposit agreement and will establish procedures to enable holders to receive the net proceeds from the redemption upon surrender of their ADSs to the depositary bank. You may have to pay fees, expenses, taxes and other governmental charges upon the redemption of your ADSs. If less than all ADSs are being redeemed, the ADSs to be retired will be selected by lot or on a pro rata basis, as the depositary bank may determine.

        The ordinary shares held on deposit for your ADSs may change from time to time. For example, there may be a change in nominal or par value, a split-up, cancellation, consolidation or any other reclassification of such ordinary shares or a recapitalization, reorganization, merger, consolidation or sale of assets of the Company.

        If any such change were to occur, your ADSs would, to the extent permitted by law, represent the right to receive the property received or exchanged in respect of the ordinary shares held on deposit. The depositary bank may in such circumstances deliver new ADSs to you, amend the deposit agreement, the ADRs and the applicable Registration Statement(s) on Form F-6, call for the exchange of your existing ADSs for new ADSs and take any other actions that are appropriate to reflect as to the ADSs the change affecting the Shares. If the depositary bank may not lawfully distribute such property to you, the depositary bank may sell such property and distribute the net proceeds to you as in the case of a cash distribution.

Issuance of ADSs upon Deposit of Ordinary Shares

        After the completion of this offering, the ordinary shares that underlie the ADSs that are being offered for sale pursuant to this prospectus will be deposited by us with the custodian. Upon receipt of confirmation of such deposit, the depositary bank will issue ADSs to the underwriters named in any applicable prospectus supplement.

        After the closing of this offer, the depositary bank may create ADSs on your behalf if you or your broker deposit ordinary shares with the custodian. The depositary bank will deliver these ADSs to the person you indicate only after you pay any applicable issuance fees and any charges and taxes payable for the transfer of the ordinary shares to the custodian. Your ability to deposit ordinary shares and receive ADSs may be limited by U.S. and English legal considerations applicable at the time of deposit.

        The issuance of ADSs may be delayed until the depositary bank or the custodian receives confirmation that all required approvals have been given and that the ordinary shares have been duly transferred to the custodian. The depositary bank will only issue ADSs in whole numbers.

        When you make a deposit of ordinary shares, you will be responsible for transferring good and valid title to the depositary bank. As such, you will be deemed to represent and warrant that:

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        If any of the representations or warranties are incorrect in any way, we and the depositary bank may, at your cost and expense, take any and all actions necessary to correct the consequences of the misrepresentations.

Transfer, Combination and Split Up of ADRs

        As an ADR holder, you will be entitled to transfer, combine or split up your ADRs and the ADSs evidenced thereby. For transfers of ADRs, you will have to surrender the ADRs to be transferred to the depositary bank and also must:

        To have your ADRs either combined or split up, you must surrender the ADRs in question to the depositary bank with your request to have them combined or split up, and you must pay all applicable fees, charges and expenses payable by ADR holders, pursuant to the terms of the deposit agreement, upon a combination or split up of ADRs.

Withdrawal of Ordinary Shares Upon Cancellation of ADSs

        As a holder, you will be entitled to present your ADSs to the depositary bank for cancellation and then receive the corresponding number of underlying ordinary shares at the custodian's offices. Your ability to withdraw the ordinary shares held in respect of the ADSs may be limited by U.S. and English considerations applicable at the time of withdrawal. In order to withdraw the ordinary shares represented by your ADSs, you will be required to pay to the depositary bank the fees for cancellation of ADSs and any charges and taxes payable upon the transfer of the ordinary shares. You assume the risk for delivery of all funds and securities upon withdrawal. Once canceled, the ADSs will not have any rights under the deposit agreement.

        If you hold ADSs registered in your name, the depositary bank may ask you to provide proof of identity and genuineness of any signature and such other documents as the depositary bank may deem appropriate before it will cancel your ADSs. The withdrawal of the ordinary shares represented by your ADSs may be delayed until the depositary bank receives satisfactory evidence of compliance with all applicable laws and regulations. Please keep in mind that the depositary bank will only accept ADSs for cancellation that represent a whole number of securities on deposit.

        You will have the right to withdraw the securities represented by your ADSs at any time except for:

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        The deposit agreement may not be modified to impair your right to withdraw the securities represented by your ADSs except to comply with mandatory provisions of law.

Voting Rights

        As a holder, you generally have the right under the deposit agreement to instruct the depositary bank to exercise the voting rights for the ordinary shares represented by your ADSs. The voting rights of holders of ordinary shares are described in "Description of Share Capital—Key Provisions of Our Articles of Association—Shares and Rights Attaching to Them—Voting Rights."

        At our request, the depositary bank will distribute to you any notices of shareholders' meetings received from us together with information explaining how to instruct the depositary bank to exercise the voting rights of the securities represented by ADSs.

        If the depositary bank timely receives voting instructions from a holder of ADSs, it will endeavor to vote the securities (in person or by proxy) represented by the holder's ADSs in accordance with the voting instructions received from such holder.

        Securities for which no voting instructions have been received will not be voted (except as otherwise contemplated herein). Please note that the ability of the depositary bank to carry out voting instructions may be limited by practical and legal limitations and the terms of the securities on deposit. We cannot assure you that you will receive voting materials in time to enable you to return voting instructions to the depositary bank in a timely manner.

Fees and Charges

        As an ADS holder, you will be required to pay the following fees under the terms of the deposit agreement:

Service
  Fees

Issuance of ADSs upon deposit of ordinary shares (excluding issuances as a result of distributions of ordinary shares)

  Up to U.S. 5¢ per ADS issued

Delivery of deposited property against surrender of ADSs

 

Up to U.S. 5¢ per ADS surrendered

Distribution of cash dividends or other cash distributions (i.e., sale of rights and other entitlements)

 

Up to U.S. 5¢ per ADS held

Distribution of ADSs pursuant to (i) stock dividends or other free stock distributions, or (ii) exercise of rights to purchase additional ADSs

 

Up to U.S. 5¢ per ADS held

Distribution of securities other than ADSs or rights to purchase additional ADSs (i.e., spin-off ordinary shares)

 

Up to U.S. 5¢ per ADS held

ADS Services

 

Up to U.S. 5¢ per ADS held on the applicable record date(s) established by the depositary bank

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        As an ADS holder you will also be responsible to pay certain charges such as:

        ADS fees and charges payable upon (i) deposit of ordinary shares against issuance of ADSs and (ii) surrender of ADSs for cancellation and withdrawal of ordinary shares are charged to the person to whom the ADSs are delivered (in the case of ADS issuances) and to the person who delivers the ADSs for cancellation (in the case of ADS cancellations). In the case of ADSs issued by the depositary bank into DTC or presented to the depositary bank via DTC, the ADS issuance and cancellation fees and charges may be deducted from distributions made through DTC, and may be charged to the DTC participant(s) receiving the ADSs or the DTC participant(s) surrendering the ADSs for cancellation, as the case may be, on behalf of the beneficial owner(s) and will be charged by the DTC participant(s) to the account(s) of the applicable beneficial owner(s) in accordance with the procedures and practices of the DTC participant(s) as in effect at the time. ADS fees and charges in respect of distributions and the ADS service fee are charged to the holders as of the applicable ADS record date. In the case of distributions of cash, the amount of the applicable ADS fees and charges is deducted from the funds being distributed. In the case of (i) distributions other than cash and (ii) the ADS service fee, holders as of the ADS record date will be invoiced for the amount of the ADS fees and charges and such ADS fees and charges may be deducted from distributions made to holders of ADSs. For ADSs held through DTC, the ADS fees and charges for distributions other than cash and the ADS service fee may be deducted from distributions made through DTC, and may be charged to the DTC participants in accordance with the procedures and practices prescribed by DTC and the DTC participants in turn charge the amount of such ADS fees and charges to the beneficial owners for whom they hold ADSs.

        In the event of refusal to pay the depositary bank fees, the depositary bank may, under the terms of the deposit agreement, refuse the requested service until payment is received or may set off the amount of the depositary bank fees from any distribution to be made to the ADS holder. Certain ADS fees and charges such as the ADS service fee may become payable shortly after the closing of this offering. Note that the fees and charges you may be required to pay may vary over time and may be changed by us and by the depositary bank. You will receive prior notice of such changes. The depositary bank may reimburse us for certain expenses incurred by us in respect of the ADR program, by making available a portion of the ADS fees charged in respect of the ADR program or otherwise, upon such terms and conditions as we and the depositary bank may agree from time to time.

Amendments and Termination

        We may agree with the depositary bank to modify the deposit agreement at any time without your consent. We undertake to give holders 30 days' prior notice of any modifications that would materially prejudice any of their substantial rights under the deposit agreement. We will not consider to be

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materially prejudicial to your substantial rights any modifications or supplements that are reasonably necessary for the ADSs to be registered under the Securities Act or to be eligible for book-entry settlement, in each case without imposing or increasing the fees and charges you are required to pay. In addition, we may not be able to provide you with prior notice of any modifications or supplements that are required to accommodate compliance with applicable provisions of law.

        You will be bound by the modifications to the deposit agreement if you continue to hold your ADSs after the modifications to the deposit agreement become effective. The deposit agreement cannot be amended to prevent you from withdrawing the ordinary shares represented by your ADSs (except as permitted by law).

        We have the right to direct the depositary bank to terminate the deposit agreement. Similarly, the depositary bank may in certain circumstances on its own initiative terminate the deposit agreement. In either case, the depositary bank must give notice to the holders at least 30 days before termination. Until termination, your rights under the deposit agreement will be unaffected.

        After termination, the depositary bank will continue to collect distributions received (but will not distribute any such property until you request the cancellation of your ADSs) and may sell the securities held on deposit. After the sale, the depositary bank will hold the proceeds from such sale and any other funds then held for the holders of ADSs in a non-interest bearing account. At that point, the depositary bank will have no further obligations to holders other than to account for the funds then held for the holders of ADSs still outstanding (after deduction of applicable fees, taxes and expenses).

Books of Depositary

        The depositary bank will maintain ADS holder records at its depositary office. You may inspect such records at such office during regular business hours but solely for the purpose of communicating with other holders in the interest of business matters relating to the ADSs and the deposit agreement.

        The depositary bank will maintain in New York facilities to record and process the issuance, cancellation, combination, split-up and transfer of ADSs. These facilities may be closed from time to time, to the extent not prohibited by law.

Limitations on Obligations and Liabilities

        The deposit agreement limits our obligations and the depositary bank's obligations to you. Please note the following:

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Pre-Release Transactions

        Subject to the terms and conditions of the deposit agreement, the depositary bank may issue to broker/dealers ADSs before receiving a deposit of ordinary shares or release ordinary shares to broker/dealers before receiving ADSs for cancellation. These transactions are commonly referred to as "pre-release transactions," and are entered into between the depositary bank and the applicable broker/dealer. The deposit agreement limits the aggregate size of pre-release transactions (not to exceed 30% of the ordinary shares on deposit in the aggregate) and imposes a number of conditions on such transactions (i.e., the need to receive collateral, the type of collateral required, the representations required from brokers, etc.). The depositary bank may retain the compensation received from the pre-release transactions.

Taxes

        You will be responsible for the taxes and other governmental charges payable on the ADSs and the securities represented by the ADSs. We, the depositary bank and the custodian may deduct from any distribution the taxes and governmental charges payable by holders and may sell any and all property on deposit to pay the taxes and governmental charges payable by holders. You will be liable for any deficiency if the sale proceeds do not cover the taxes that are due.

        The depositary bank may refuse to issue ADSs, to deliver, transfer, split and combine ADRs or to release securities on deposit until all taxes and charges are paid by the applicable holder. The depositary bank and the custodian may take reasonable administrative actions to obtain tax refunds and reduced tax withholding for any distributions on your behalf. However, you may be required to provide

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to the depositary bank and to the custodian proof of taxpayer status and residence and such other information as the depositary bank and the custodian may require to fulfill legal obligations. You are required to indemnify us, the depositary bank and the custodian for any claims with respect to taxes based on any tax benefit obtained for you.

Foreign Currency Conversion

        The depositary bank will arrange for the conversion of all foreign currency received into U.S. dollars if such conversion is practical, and it will distribute the U.S. dollars in accordance with the terms of the deposit agreement. You may have to pay fees and expenses incurred in converting foreign currency, such as fees and expenses incurred in complying with currency exchange controls and other governmental requirements.

        If the conversion of foreign currency is not practical or lawful, or if any required approvals are denied or not obtainable at a reasonable cost or within a reasonable period, the depositary bank may take the following actions in its discretion:

        The deposit agreement and the ADRs will be interpreted in accordance with the laws of the State of New York. The rights of holders of ordinary shares (including ordinary shares represented by ADSs) are governed by the laws of England and Wales.

        AS A PARTY TO THE DEPOSIT AGREEMENT, YOU WAIVE YOUR RIGHT TO TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF THE DEPOSIT AGREEMENT OR THE ADRs AGAINST US AND/OR THE DEPOSITARY BANK.

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PLAN OF DISTRIBUTION

        The ADSs may be offered and sold by purchasers, transferees, donees, pledgees or other successors in interest, directly or through brokers, dealers, agents or underwriters who may receive compensation in the form of discounts, commissions or similar selling expenses paid by us or by a purchaser of the ADSs on whose behalf such broker-dealer may act as agent. Sales and transfers of the ADSs may be effected from time to time in one or more transactions, in private or public transactions, on The Nasdaq Global Select Market, in the over-the-counter market, in negotiated transactions or otherwise, at a fixed price or prices that may be changed, at market prices prevailing at the time of sale, at negotiated prices, without consideration or by any other legally available means. If sales and transfers are effected by means of an underwriting, underwriting discounts will not exceed 8% of the proceeds of the offering. Any or all of the ADSs may be sold from time to time by means of:

        To the extent required with respect to a particular offer or sale of ADSs, we will file a prospectus supplement, which will accompany this prospectus, to disclose the number of ADSs to be sold and the purchase price. The prospectus supplement will set forth the terms of the offering, including the names of any underwriters, dealers or agents, the purchase price of such securities and the proceeds to us from such sale, any underwriting discounts and commissions or agency fees and other items constituting underwriters' or agents' compensation, any public offering price and any discounts or concessions allowed or paid to dealers or any securities exchange on which such securities may be listed. Any public offering price, discounts or concessions allowed or paid to dealers may be changed from time to time.

        We may grant to the underwriters options to purchase additional ADSs, at the public offering price, with additional underwriting commissions or discounts, as applicable, set forth in the prospectus supplement. The terms of any such option will be set forth in the prospectus supplement for those ADSs.

        Sales to or through one or more underwriters or agents in at-the-market offerings will be made pursuant to the terms of the applicable underwriting sales or distribution agreement with the

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underwriters or agents. Such underwriters or agents may act on an agency basis or on a principal basis. During the term of any such agreement, ADSs may be sold on a daily basis on any stock exchange, market or trading facility on which the ADSs are traded, in privately negotiated transactions or otherwise as agreed with the underwriters or agents. The agreement will provide that any ADSs sold will be sold at negotiated prices or at prices related to the then prevailing market prices for our ADSs. Therefore, exact figures regarding proceeds that will be raised or commissions to be paid cannot be determined at this time and will be described in a prospectus supplement. Pursuant to the terms of the agreement, we may also agree to sell, and the relevant underwriters or agents may agree to solicit offers to purchase, blocks of our ADSs. The terms of each such agreement will be described in a prospectus supplement.

        Any discounts, concessions or commissions received by underwriters or agents and any profits on the resale of securities by them may be deemed to be underwriting discounts and commissions under the Securities Act. Unless otherwise set forth in the applicable prospectus supplement, the obligations of underwriters to purchase the offered securities will be subject to certain conditions precedent, and such underwriters will be obligated to purchase all such securities, if any are purchased. Unless otherwise indicated in the applicable prospectus supplement, any agent will be acting on a best efforts basis for the period of its appointment.

        We may enter into derivative transactions with third parties or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with those derivatives, such third parties (or affiliates of such third parties) may sell securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, such third parties (or affiliates of such third parties) may use securities pledged by us or borrowed from us or others to settle those sales or to close out any related open borrowings of stock, and may use securities received from us in settlement of those derivatives to close out any related open borrowings of stock. The third parties (or affiliates of such third parties) in such sale transactions will be underwriters and, if not identified in this prospectus, will be identified in the applicable prospectus supplement (or a post-effective amendment).

        We may loan or pledge securities to a financial institution or other third party that in turn may sell the securities using this prospectus. Such financial institution or third party may transfer its short position to investors in our securities or in connection with a simultaneous offering of other securities offered by this prospectus.

        The aggregate net proceeds to us from the sale of ADSs will be the purchase price of such ADSs less any discounts, concessions or commissions.

        The ADSs covered by this prospectus may become qualified for sale under Section 4(1) of the Securities Act or Rules 144 or 145 promulgated thereunder, whereupon they may be sold pursuant to such provisions rather than pursuant to this prospectus.

        We may indemnify agents, underwriters and dealers against certain liabilities, including liabilities under the Securities Act. Our agents, underwriters, dealers and remarketing firms, or their affiliates, may be customers of, engage in transactions with or perform services for us, in the ordinary course of business.

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LEGAL MATTERS

        Certain legal matters of United States federal law and New York State law will be passed upon for us by Mayer Brown LLP. The validity of the ordinary shares represented by the ADSs and certain other legal matters as to English law will be passed upon for us by Mayer Brown International LLP, our English counsel.


EXPERTS

        The consolidated financial statements of Adaptimmune Therapeutics plc as of December 31, 2015, June 30, 2015 and 2014, and for the six month period ended December 31, 2015 and each of the years in the three year period ended June 30, 2015, which have been prepared under U.S. generally accepted accounting principles ("U.S. GAAP") and which were included in Item 9.01 of the Form 8-K dated July 8, 2016, have been incorporated by reference herein in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing.

        The consolidated financial statements of Adaptimmune Therapeutics plc prepared under International Financial Reporting Standards as issued by the International Accounting Standards Board, which are included in the June 30, 2015 Annual Report on Form 20-F and the December 31, 2015 Transition Report on Form 20-F (which filings are incorporated by reference herein), are superseded by the consolidated financial statements prepared under U.S. GAAP included in Item 9.01 of the Form 8-K dated July 8, 2016, incorporated by reference herein.


SERVICE OF PROCESS AND ENFORCEMENT OF JUDGMENTS

        We are incorporated under the laws of England and Wales. Some of our directors and officers reside outside the United States, and a substantial portion of our assets and all or a substantial portion of the assets of such persons are located outside the United States. As a result, it may be difficult for you to serve legal process on us or our directors and executive officers (as well as certain directors, managers and executive officers of the finance subsidiaries) or have any of them appear in a United States court.

        We have appointed Adaptimmune LLC as our authorized agent upon whom process may be served in any action instituted in any U.S. federal or state court having subject matter jurisdiction in the Borough of Manhattan in New York, New York, arising out of or based upon the ADSs, the deposit agreement or the underwriting agreement related to such ADSs.

        Mayer Brown International LLP, our English counsel, has advised us that there is some doubt as to the enforceability in the United Kingdom, in original actions or in actions for enforcement of judgments of U.S. courts, of civil liabilities based solely on the federal securities laws of the United States. In addition, awards for punitive damages in actions brought in the United States or elsewhere may be unenforceable in the United Kingdom. An award for monetary damages under the U.S. securities laws would be considered punitive if it does not seek to compensate the claimant for loss or damage suffered and is intended to punish the defendant. The enforceability of any judgment in the United Kingdom will depend on the particular facts of the case as well as the laws and treaties in effect at the time. The United States and the United Kingdom do not currently have a treaty providing for recognition and enforcement of judgments (other than arbitration awards) in civil and commercial matters.

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American Depositary Shares

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Representing            Ordinary Shares



PRELIMINARY PROSPECTUS SUPPLEMENT

                        , 2017


Joint Book-Running Managers

Citigroup

Cowen and Company

Leerink Partners