Sadiq Khan appeared on Sky News today to talk about his favourite subject. Was it knife crime and rising levels of violence in London? No, of course not! That's something he actually has some responsibility for. In actual fact he was ranting about Brexit. You know, for a change. After posturing about the ending of free movement, which he described as "wrong, callous and cruel", he announced that the government should be revoking Article 50. You know, because he said so. Khan probably didn't expect Sky's Kimberley Leonard to bite back. Glorious!