The economic debate during this election campaign has not exactly been edifying. Labour’s numbers don’t add up, while the Conservatives have chosen not to even pretend that they’ve costed the impact of their policies. The words of the home secretary, Amber Rudd, last Thursday, are particularly breathtaking. Her response to the latest immigration statistics, showing a significant fall in net migration, was the following: “It’s good that the overall figure has come down now by nearly a quarter in a year. We’re determined to make sure that we do continue to reduce the overall net migration number.”

It is worth unpicking this. The fall in net migration was driven mostly by more British and EU citizens leaving and fewer moving or returning. In other words,