By Huw Jones

LONDON (Reuters) - Veterans of the City of London's financial services industry are setting up a forum to help the British government in Brexit talks with the European Union, people involved in the project said on Thursday.

Britain's shock vote to leave the bloc has forced financial firms to rethink their business strategy which has until now depended on having an EU "passport" to operate across the region from a base in London.

Daniel Hodson, a former chief executive of London derivatives exchange LIFFE which is now part of ICE <ICE.N>, said the new group - initially known as City United - aimed to bring together under one roof those in the financial sector who backed and opposed Brexit.

Hodson was director of Vote Leave which campaigned for Brexit in last month's referendum.

He said other members of the group included another City of London veteran, Anthony Belchambers, a former head of the Futures and Options Association. Graham Bishop, a pro-EU consultant who has advised EU institutions, is also a member.

"There is a need to bring those who supported both sides together in an effective way that recognizes the political reality of the situation," Hodson told Reuters.

The group, which will be renamed the Financial Services Negotiation Forum, will have a formal launch in September.

The City of London Corporation, which administers the capital's "Square Mile" financial district had backed staying in the EU. TheCityUK, which promotes Britain's financial sector, had warned that Brexit could damage competitiveness.

Hodson said it was clear from government statements that continued full membership of the EU's single market was not on the table and therefore the financial sector must come up with a common position to help the government with trade talks.

"We will be independent and fact based ... TheCityUK will play a very important part and we will be working with them," Hodson said.

Other supporters of the new group spoke of "bitterness and angst flying around the City" and the need to get coherence around what needs to be done between the leave and remain camps.

Richard Tice, chief executive of Quidnet Capital and who co-chaired the referendum campaign group Leave.EU. said the referendum result was clear and bodies like the City of London should get on with making it work.

The City of London Corporation and TheCityUK had no comment.

The Chartered Institute for Securities and Investment (CISI) said on Tuesday that since the referendum, financial sector had lacked a loud and visible champion communicator at a time of great uncertainty.

"There have been a number of discussions beneath the radar, but that's not good enough," CISI Chief Executive Simon Culhane said in a statement.

"Instead there has been almost total silence and zero direction or reassurance," Culhane said.

(Reporting by Huw Jones. Editing by Jane Merriman)