LONDON (Reuters) - Foreign minister Philip Hammond, the leading candidate to be Britain's next finance minister, said on Tuesday he would fight for British financial services to retain access to the European Union's single market after the vote to leave the trading bloc.Hammond, speaking at a British Bankers' Association event in London, said financial services was probably the industry most directly affected by the political upheaval, according to two people who attended the meeting."Access to the single market is crucially important to your industry," Hammond said, according to the two attendees. They cited Hammond as saying that there was a risk the banking industry could move to another European city, but it would be difficult.Theresa May will take over from David Cameron as British prime minister on Wednesday. After the political shock caused by Britain's vote to leave the EU, she is expected to immediately start putting together a new cabinet.Hammond is the person most likely to replace George Osborne as finance minister at 2/7, according to bookmaker Ladbrokes (LON:LAD), followed by Chris Grayling at 4/1 and Sajid Javid at 6/1.