The super-rich can up-anchor to flee taxes – and the middle classes will, too

other developed nation had lost as many skilled citizens. Older estimates put the total number of expats at

4.7 million, and UCL research found the 300,000 who emigrate every year to be disproportionately privileged, with an average age of 42.

Firms are preparing for a future of unprecedented global mobility, a period abroad is increasingly vital to a successful career, and even countries cutting migration have no wish to turn skilled workers away.

Obviously not everyone wants to be an émigré, and it’s not all about money. But Britain’s attractions are not as compelling as we might hope. Our cost of living is high, our climate middling and, as Philip Hammond reminded us this week, the rates of tax we levy are “recognisably European”. It’s outrageous that scores of doctors, whose education we subsidised, are emigrating to Australia, but it’s also a warning of the potential consequences of a Left-induced brain drain.

Whatever they’ve done to rates, historically there has been a limit to what the Treasury can sustainably extract from the economy as a percentage of GDP, as companies and individuals manage their affairs so as to minimise their liabilities, and by some measures we are already approaching it. If ordinary people are growing more likely to move overseas, that ceiling could come down further. This means two things. First, if Corbyn hikes taxes on the middle classes to fund pet projects, he will have to introduce draconian measures to trap people and capital in Britain. Less insanely, the Tories need to abandon their indifference towards tax cuts. Outside the EU, in a hyper-competitive world, we need to be as attractive to the aspirational middle class as we can.