There is something really ugly in Sadiq Khan’s description of stabbings in London as the ‘human cost of austerity’. What’s he saying? That being poor makes you a violent maniac? That being hard-up increases your likelihood of wanting to take a knife from the kitchen drawer and use it to slice some kid’s face? Does he really believe that individuals see things closing down — youth centres, libraries, mental-health programmes — and think to themselves: ‘This is bad.