In a letter released by the Vote Leave group ahead of a June 23 referendum, the City bosses said getting out of the EU would help strengthen London's position as the only financial capital to rival New York.

The investors said that while membership had been good for Britain and London since 1973, it no longer made sense as the EU had failed to support innovation and was now tied to a euro zone which many signatories feared was doomed.

"There is scant evidence that the EU will foster or support the kind of innovation which is essential if Europeans are to compete with the rest of the world," the signatories said.

"The EU is now shackled to the euro, a project doing damage to the social and economic fabric of member countries, including high youth unemployment. Many of us worry that the euro zone’s problems may prove insurmountable."

The list of signatories included Odey, a founding partner at Odey Asset Management, Marshall, chairman of Marshall Wace, Peter Hargreaves, a founder of investment firm Hargreaves Lansdown (>> Hargreaves Lansdown PLC) and Michael Geoghegan, a former CEO of bank HSBC (>> HSBC Holdings plc).

Other signatories included Dominic Burke, group CEO at Jardine Lloyd Thompson (>> Jardine Lloyd Thompson Group plc), Peter Cruddas, chief executive at CMC Markets, and Luke Johnson, founder of Risk Capital Partners. All 100 names were not supplied by Vote Leave.

The message that London would prosper after a British exit contrasts with a host of warnings over recent months from U.S. investment banks, the Bank of England, the City of London Corporation and pro-EU British ministers that an exit would undermine London.

"LONDON CAN THRIVE"

Many financiers say a British exit would sap London of its wealth, hammer sterling, undermine the world's fifth largest economy and prompt some traders to move their business to other financial centres such as New York and Singapore.

But the signatories of the Vote Leave letter said continued EU membership was now a threat to London's prosperity.

"We worry that the EU’s approach to regulation now poses a genuine threat to our financial services industry and to the competitiveness of the City of London," the letter said.

"Assuming good political leadership and an effective regulatory environment, we believe that the City is most likely to strengthen its lead as the world's largest international financial centre, and continue to make a major contribution to the UK economy and employment, outside the EU but with continued access to its capital markets," the letter said.

Since British exchange controls were scrapped in 1979, London has thrived as a centre for everything from foreign exchange and bonds to derivatives and fund management, making it the largest net exporter of financial services in the world.

"Far from the picture of doom and gloom painted by the Government, it is clear that the City of London would not only retain its pre-eminence as the world’s most important financial centre, but would also thrive after freeing herself from the EU’s regulatory shackles," said Vote Leave boss Matthew Elliott.

(Writing by William Schomberg; editing by Guy Faulconbridge and Toby Chopra)

By William Schomberg and Guy Faulconbridge