Ed Miliband is favourite to become the next prime minister according to bookies followed by the London Mayor. Andy Burnham, the shadow health secretary, is third while Theresa May, the Home Secretary, is fourth.

Stanley Johnson has frequently spoken in favour of his son’s apparent desire to take over the Tory leadership when it becomes available.

He has previously bemoaned the fact that only MPs can challenge for the leadership – which would currently rule the London Mayor out of the race, though he is standing for a seat in this election – and called for reform.

“It does seem to me to be odd that the universe from which future leaders of the Conservative party can be selected is strictly limited to serving members of the House of Commons,” Stanley Johnson said.

He added: “I can’t think of another democracy in the world which has so restricted a view of the eligible candidates for the highest office.”