Half a million foreigners have apparently entered the UK since 2007 without proper passport checks. Anyone who thinks this posed a major threat to national security is mad. There has been no crime wave, no jihadist uprising, no outbreak of suicide bombing. One wonders what immigration control is for. Yet the words foreigner and border control trigger such hysteria that Tuesday’s Daily Mail could profess itself “terrified”. So the home secretary, Theresa May, had to indulge in Westminster’s favourite blood sport: departmental reorganisation. She took her courage in both hands and “split the UK border agency in two”. That should do the trick.