Stuart Fraser, policy chairman, City of London Corporation

There is undoubtedly a tipping point at which the advantages of being based in London no longer outweigh the financial implications of having to pay such high rates of tax. Any further changes to the UK tax regime must be considered in a global context.

That said, given the prevailing financial and political situation in the UK, it is easy to understand why increasing the tax burden on large firms and high earners, particularly in financial services, is such a popular course of action.

I do not believe we will see banks closing their doors and leaving the UK or thousands of bankers packing their bags simply because the government is planning to tax them at a higher rate.

While firms and their employees may be able to pay less tax by moving overseas, particularly to Asia's emerging markets, this would also deny them access to the breadth of world-class services the City offers and the quality of life enjoyed by London's residents.

But there are signs that our international competitiveness is under threat. Firms are finding it harder to place employees in the UK and highly mobile industry sectors, such as hedge funds, and certain high-earning individuals (usually those who pay the highest taxes) are considering going overseas.

This cannot be allowed to continue. Not only is the financial services industry a vital asset to the UK, but the funds raised from the bonus supertax, or from raising the top rate of income tax, are nothing compared to the money the Treasury will lose out on if we fail to implement a stable, consistent and, most importantly, predictable fiscal system.

Richard Murphy, director, Tax Research LLP

Whenever a change in tax for the better off or companies is promoted, the perennial threat is that it will lead to an exodus of talent from the UK. Now in my fifties, I've been hearing this claim throughout my career. So far it has always rung hollow. There's been no evidence it has ever happened, and I strongly suspect it never will. There are three good reasons for saying this.

First, the UK tax system is generous to the best off in our society. They have the lowest overall rates of tax and the introduction of a 50 per cent rate will not do much to change that. It just means the incentive reward from avoiding tax is increased. With few constraints on that activity in place at present, such changes will have little impact.

Second, there is scarce evidence of overseas demand for UK-raised talent. Few leave Britain to earn less, or become jobless. And third, in many locations abroad tax rates will be even higher. Where they're not—such as in Switzerland—the quality of life for those used to London might fairly be called challenging. You have to be truly dedicated to money, and money alone, to leave the UK given these facts.

The same is true for companies. Unless you're heading for a tax haven—and want to risk a likely challenge from Revenue & Customs—the UK tax rate is low, reliefs generous and the new offshore regime almost too relaxed for the economy's good. If tax is that crucial to companies' bottom line the chance that they'll be adding much to the UK top line is low. In that case, it's unlikely we'll miss them.