UPDATE 1-UK Stocks-Factors to watch on March 7

(Adds company news item, futures) March 7 (Reuters) - Britain's FTSE 100 futures were flat ahead of the cash market open on Tuesday. * SHAWBROOK: British bank Shawbrook Group Plc said on Tuesday it had rejected an improved proposal be bought by two private equity firms for 825 million pounds ($1 billion). * DIRECT LINE: British insurer Direct Line reported a 22 percent fall in full-year operating profit on Tuesday, after the government changed the way personal injury claims are