Sadiq Khan admits that he believes voters “got it right” on December 12. “Hand on heart, did we deserve to win the general election?” the Labour mayor of London asks. “Probably not, so the British public got it right.”

Khan, who is standing for re-election on May 7, calls the result “catastrophic”. He is at pains to reject Jeremy Corbyn’s claim Labour “won” the argument, stating baldly: “We lost the argument.”

I meet Khan and his labrador Luna on Tooting Common, south London. As Labour’s most popular serving politician, according to YouGov, his life is a stream of selfie requests: “Only twice have I said no. Once when I was rushing to catch a plane, the other when I was at A&E with a family