It's working… We think a smart company would want to invest [in Britain]." Pfizer's Scottish-born boss, Ian Read, wrote in a letter to David Cameron that he viewed the company's "partnership with the UK government as a critical part of this potential transaction". "We believe the industrial logic for a combination between Pfizer and AstraZeneca is compelling," he wrote. Read has just returned to the US after a two-day trip to London, where he met the chancellor, George Osborne, other government ministers and major AstraZeneca shareholders.