Premiership footballers are quaking in their studded boots at the thought of handing over more of their millions to HM Revenue and Customs. Celebrities such as Michael Caine and scruffy bedroom artist Tracey Emin have voiced their displeasure and the financial world has labelled the move “unfair, complex, inefficient and damaging”.

However, will this threatened exodus actually materialise if the 50p rate does come into force?

Arguing the case against the new tax band are a string of City institutions and economic think tanks. Take the CBI for example. Its president, Martin Broughton, claims the 50p rate had been introduced to divert attention from the government’s “failure” to control its ballooning budget deficit.

Instead of attacking the wealthy, Broughton suggests that if business were responsible for the deficit it would reform public sector pensions, tackle  the “mismanagement” of services and discontinue non-core activities.

Broughton says: “In the government’s position, we would start educating the public to accept that it is not the government’s role to address every issue in society. How many of the 1,000 quangos costing £65bn a year do we really need?”

But, perhaps the most damning comments on the new rate come from the Centre for Policy Studies. It argues the tax, which will raise just £2.4bn of new revenue according to Treasury figures, is “nugatory in comparison with current government borrowing requirements of £175bn.”

Its report on the hike says wealthy workers will shun Britain, which will have the highest tax regimes of any member of the G8 richest nations. The report also shows that the richest one per cent of people in Britain already provide 23.9 per cent of all income tax revenues, an increase on the 21.3 per cent at the beginning of the millennium.

Therefore, rather than raking in an extra £2.4bn, the Treasury could actually lose money. However extraordinary that sounds, it is also the firm belief of the bean counters at the Centre for Economic and Business Research (CEBR).

The CEBR claims the government will lose £800m million a year and tens of thousands of jobs will be lost if the 50p bracket is pushed through. Its findings claim 25,000 wealthy tax payers will depart these shores, taking with them up to 140,000 jobs and a fall in GDP in the City of London of three per cent.

But will it really happen? Will the wealthy escape high-tax Britain in their tens of thousands? Will entrepreneurs be dissuaded from building a business and their fortune on these shores?

Well, if the example of the 1970s is anything to go by, then no. Many threatened to shoot off to more tax friendly as well as sunnier climes, but not so many actually did. But things have moved on since the 1970s. Could the mass exodus really take place in this new age of mobile technology and labour?

Well, just compare the 1970s to now. Back then you could not jump on a cheap flight to just about anywhere in Europe, and once there hook up to the internet and run your business as easily, more efficiently and less expensively than on British shores.

What’s more, there’s nothing stopping you trading from a friendlier tax environment while maintaining a London presence. The same technology that allows me to write this article from a country retreat in Devon will allow those threatening to escape a harsher British tax system to do just that.

For me, the threat this time round is a genuine one. The only hope is that the expected Conservative government dumps the 50p tax hike. But, while David Cameron has hinted at such a move he has not guaranteed it. Without such a guarantee entrepreneurs, jobs and the entire British economy will suffer.