Heathrow expansion: Free MPs vote on third runway would be 'absolute dereliction of duty', says top Tory

Former Tory party chairman Grant Shapps calls for Theresa May to lay down the law to her MPs over another runway serving London

Airline staff wave flags at the arrival of a British Airways Airbus A380 at Heathrow in 2013 (Getty)

A free vote on whether to expand Heathrow Airport – proposed in a leaked Government paper – would be an “absolute dereliction of duty”, a senior Tory MP has told Theresa May.

Former party chairman Grant Shapps hit out at the suggestion that Cabinet ministers and other Conservative MPs would be able break ranks on such “an enormous decision for Britain’s future”.

“It would be leaving the future of our infrastructure pretty much to chance. Who knows which way that vote would go?” Mr Shapps said.

The criticism followed the revelation that the Prime Minister could seek to resolve her Heathrow headache through a “potential waiving of collective responsibility” – a free vote for her MPs.

Cabinet big-hitters Boris Johnson, the Foreign Secretary, and Education Secretary Justine Greening are among those fiercely opposed to expanding Heathrow to provide London with another runway.

A document discussing a free vote was filmed by a passenger on the London Underground and given to Channel 4 News, ahead of this autumn’s decision on expanding airport capacity.

Details of the proposal were contained in an email sent to Sue Gray, the director general of the Cabinet Office's propriety and ethics team.

The document suggests that “one route for waiving collective responsibility would be a free...” with the next few words then obscured by the thumb of the woman holding the printout.

The sentence continues “... allowing ministers to speak against the Government's position in the House”.

The document goes on to refer to the differing positions held by Liberal Democrats and Conservatives during the Coalition government and to Cabinet colleagues being in opposing camps in the EU referendum campaign.

In July last year, the Davies Commission recommended the building of a third runway at Heathrow, but the Department for Transport announced that further investigation into noise, pollution and compensation would be carried out before a decision was made.

David Cameron was expected to announce which project would get the go-ahead – Gatwick is also seeking permission to build another runway – after the EU referendum, but his resignation following the Brexit vote left the decision to Ms May's new Government.

Mr Shapps said a free vote would be a “terrible” idea and a “fudge”, saying he did not believe the Prime Minister would embrace the suggestion.

He said: “If it is being considered beyond the civil service, I think it would be completely wrong and a dodge on an enormous decision for Britain’s future.”

A spokesman said: "The Government remains committed to taking a decision on airport expansion and delivering additional runway capacity as planned by 2030. We will set out next steps in due course."