“Great swathes of the country remain hostile to the Conservatives,” he added, noting that there is still only one Tory MP in Scotland and that the Conservatives only hold 20 of the 124 urban seats in the north of England and the Midlands.

“The economic recovery is, of course, good political news for the Tories. But the party will not be on a glide path to a majority if it doesn’t make determined and consistent efforts to broaden its appeal to working people, ethnic minority voters, people living in towns, cities and their suburbs and voters living outside of the traditional Conservative heartland,” Mr Skelton said.

Mr Skelton’s views were privately echoed by Conservatives in Government, who were exasperated by the Mayor’s remarks.

One Tory source sarcastically described Mr Johnson’s comments as “as helpful as ever” and insisted that ministers will never make such bullish statements about the election and the economy.

“We absolutely cannot be seen as complacent or like we think victory is in the bag – our message has to be that the work continues and we are the only party who will see it through.”