Sadiq Khan warns that the Labour Party must change dramatically to defeat Boris Johnson.
The London mayor said he feels "nervous" when Labour figures say they "won the argument" at the general election.
Khan said that Labour cannot just change its lead singer, but its band and music too.
"I used to be a lawyer, and if I ever said to a client after losing a case 'well at least we won the argument,' I can imagine what their response would be," he told Business Insider.
The London mayor has not...