It’s the seductive promise to control immigration that’s spinning us out of the single market. The referendum would never have been won if Leavers had campaigned solely on vague concepts of sovereignty or the role of the European Court of Justice. Now Theresa May has confirmed that we are about to rip up our relationship with the EU, but in return we’ll achieve what Britain voted for: we’ll get back control on immigration.

Well, marvellous. It’s what the voters wanted and what they’re going to get. Except that the evidence suggests the opposite.

The government has always been in complete control of its rules about immigration from outside the EU. And yet the numbers arriving from far-flung countries have climbed dramatically over the decades. Even