At Prime Minister’s Questions today, Jeremy Corbyn devoted all six of his questions to Brexit for the first time in ages. But that didn’t stop Theresa May shoehorning in a bad joke about the Czech spy story. Once the Labour leader had finished, she said:"Normally he stands up every week and asks me to sign a blank cheque. And I know he likes Czechs, but really…"While Philip Hammond did his best to laugh along, Corbyn pretended to yawn. Meanwhile, political journalists on Twitter were left reeling.