Boris Johnson would destroy Labour opinion poll lead if he were leader

An opinion poll found that Boris Johnson would demolish Labour's lead in the polls if he replaced David Cameron (Getty Images)

Boris Johnson would demolish Labour’s opinion poll lead if he replaced David Cameron as Conservative leader, an opinion poll found today.

With Mr Cameron in charge, the Tories trail by six points, winning 31 per cent backing compared with 37 per cent for Labour, according to research by YouGov.

However, the figures turned around when people were asked to imagine how they would vote if the London Mayor was Conservative leader. Asked to choose between Mr Johnson and Ed Miliband, the two parties were level-pegging on 37 per cent each.

The findings, for the London Evening Standard, underline the Mayor’s ability to reach out to wavering voters.

They also suggest his bruising encounter on Sunday with the BBC’s Eddie Mair, who called him a “nasty piece of work” could have even boosted his popularity. When the same question was asked a week ago, the result was a two-point Labour lead, at 38 to 36.

YouGov found that the “Boris effect” was strongest among younger voters and also discovered that he would attract one third of supporters of the UK Independence Party back to the Conservatives.

Mr Johnson this week gave his clearest signal of his ambitions to become Tory leader when he said he would “have a crack“ at the job “if the ball came loose from the back of a scrum”.

Several Conservative MPs are rumoured to be ready to give up their seats for him in 2015 to enable him to be in parliament after the election and in a place to mount a leadership bid.