In any case, if it is primarily unskilled migration we wish to deter, there are better solutions. One, proposed by US economist Gary Becker, is to auction or otherwise charge for work visas, thereby setting a price that would match supply and demand, raise money for the government and generally be a deterrent to all but relatively highly paid, skilled workers.
Another, quite similar, approach would be that already applied in Singapore – arguably the world’s most open economy – of charging companies a levy for employing foreign workers below a certain wage threshold, with the extra taxes so raised channelled into productivity-enhancing schemes, such as training for local workers.
Freedom to hire as companies see fit is thereby preserved, but at the same time the initiative helps raise local wages, decreases reliance on immigrant labour, and provides a powerful incentive to adopt less manpower-intensive practices. Better productivity ultimately means higher wages for all.
Since adopting the scheme, Singapore’s growth in immigrant labour has slowed from 60,000 in 2011 to just 16,000 the year before last, excluding domestic workers and construction.
Any such positive discrimination in favour of nationals would no doubt fall foul of the single market’s free-movement rules. Yet if the EU doesn’t change, there soon won’t be an internal market left to defend. The EU refused Mr Cameron, and thereby brought Brexit on itself. We can but hope that Europe’s leaders aren’t quite so stupid when it comes to Mrs May.