George Osborne, shadow chancellor, has promised the City that a Eurosceptic Conservative government would not become isolated in Europe and that it would be “prepared to trade” with other member states to defend Britain’s financial services sector.

Mr Osborne’s comments, in an interview with the Financial Times, will be viewed as a warning to Eurosceptic hardliners in his own party that a Tory government will not put dogma in front of defending “Britain’s national interests on financial services”.

He said he would base a Tory minister in Brussels “for the next year or two” to ensure a “much more aggressive Treasury presence” as EU legislation is drafted. While he insisted that a Tory government would adopt a Eurosceptic policy and fight to regain certain powers in social policy and over the charter of fundamental rights from Brussels, the overall policy would have to be “deliverable”.

“We have to be realistic at how we play the European game,” Mr Osborne said, using words that might reassure some City sceptics who believe the shadow chancellor tends to put party politics above serious policy.

“We’re prepared to trade some other things in order to secure Britain’s vital national interests on financial services.”

Mr Osborne declined to say what deals a Tory government might strike, but wanted no repeat of the confrontation in the 1990s when the administration of John Major tried to disrupt EU business in a row over beef exports.

“I don’t think you want to repeat the experience of the beef war,” he said.

The shadow chancellor also set out a vision to give Britain “the most attractive and competitive corporate tax regime of any major economy in five years’ time”, starting with an “emergency Budget” within 50 days of a Tory election victory.

He would start by cutting corporation tax from 28p to 25p – funded by ending tax allowances and exemptions – but said he wanted to go much further when the public finances allow.

While he said he could not go as far as Ireland’s 12.5 per cent rate, he said that low headline corporation tax rates acted as “a kind of advert for the country”.

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The CBI employers’ organisation wants a medium-term target of 18 per cent.

Mr Osborne promised a review of the controlled foreign company tax regime, aiming to attract multinationals to Britain, and he pledged also to create a new tax regime for intellectual property, where revenues from brands, trademarks and patents could be taxed at less than 10 per cent.

Mr Osborne insists a Tory government would move faster and more decisively to cut the deficit than Alistair Darling, chancellor, who wants to halve borrowing to 5.5 per cent of gross domestic product by 2014.

Additional reporting by Vanessa Houlder and Brian Groom