It has been a busy week for ­immigration stories. But amid the claims and counter claims about statistics, there is a ­worrying political trend emerging if you look through the smoke and mirrors.

After years of growing immigration, Britons seem more anxious than ever about the scale and impact of immig­ration. Responding to this public concern, both main parties are eager to outdo each other in convincing voters that they can reduce the number of newcomers from outside the European Union. The government and the opposition are engaged in an “arms race” on stricter admission criteria and seem to agree that explicit or implicit annual limits on the numbers of economic migrants are the way forward. But what may seem like a politically attractive strategy in the short term is likely to be operationally impractical, economically painful and politically toxic if this race runs its course.