The prime minister and Labour’s NEC were absolutely right to block Andy Burnham’s attempt to stand in the Gorton and Denton by-election (Metro, Mon). Mr Burnham has repeatedly said he wants to continue the ‘important work’ he is doing as mayor of Greater Manchester. But then, of course, this is all about his ambition to challenge Sir Keir Starmer for the Labour leadership. Sir Keir and his cabinet already have a difficult job navigating national challenges. Mr Burnham was elected to serve Manchester and that is where his focus should remain.