Britain's influence in Europe remains strong despite being outside the eurozone, the chancellor has claimed.

Opening the new European headquarters of Lehman Brothers in London on Monday, Gordon Brown insisted that the government would continue with its policies aimed at helping business.

"With a significant proportion of euro business transacted in London - in fact, more international financial services business in euros is done in London than in any city inside the euro area - the UK's influence remains strong," he said.

"I am proud that London plays host to a greater number of foreign bank branches and subsidiaries than any other city in the world; has the largest share of global cross border bank lending; and with the London Stock Exchange, the largest trading centre for foreign equities and international bonds in the world, and the Foreign Exchange Market, the largest and most important in the world, you lead for Britain in the world - generating £50 billion of wealth each year, providing work for over one million people, and accounting for over five per cent of UK output.

"And I can affirm to you that, in all the decisions we make, the government will continue to do all in our power to ensure that London remains a pre-eminent financial centre."

Tories' City success

His comments came as media reports suggest that City leaders are returning to the Conservative Party.

It follows a hard push from the party to regain their traditional supporters who defected to Labour at the last two general elections.  Indeed, the FT reported on Monday that more investment bankers and chief executives are contributing funds to the Tories, after leaving the party under the leaderships of William Hague and Iain Duncan Smith.

Shadow chancellor Oliver Letwin cited a dissatisfaction with the government for the increase in support.

"The fact that people in the City are contributing to us in such numbers is a clear sign of disillusionment with the government and of the growing credibility of the Conservative Party," he said.

His comments were echoed by Howard Leigh, a party treasurer and chief executive of Cavendish Corporate Finance.

"The City recognises that the party is in good shape and this is the first time I have received unsolicited text from City people instead of having to ask them," he said.