A Tory plot to oust David Cameron has been revealed by a backbench MP who confirmed he was asked to consider a "stalking horse" leadership challenge against the Prime Minister.

Colonel Bob Stewart said he was approached by two party colleagues before the summer recess with the proposal but that he told them to "get lost" and rejected the idea as "silly".

Details of the scheming was exposed by the Mail on Sunday, which also reported that Tory MP Zac Goldsmith had offered his safe Tory seat to Boris Johnson.

The London mayor is understood to have discussed the idea of standing in a by-election as part of a bid to fight plans to expand Heathrow Airport.

Ministers confirmed last week that the final decision on UK airport expansion will be taken by the next government.

Mr Goldsmith has vowed to resign as the MP for Richmond in south west London if the Government revives controversial plans for a third runway at Heathrow airport.

The newspaper said that the idea of Mr Johnson fighting the subsequent by-election to secure a return to the Commons and the chance to challenge for the leadership was made in talks to discuss how best to oppose the airport expansion.

The idea was said to have been dismissed "out of hand" by the Mayor, whose position as a potential challenger to Mr Cameron has been reinforced by the successful London Olympics.