Airport report on expansion of Heathrow or Gatwick fails to settle debate after long delays

But it is likely to keep alive the option of building a second runway at Gatwick

Both Heathrow and Gatwick, pictured, have supporters in high places (BAA)

A three-year inquiry into airport capacity in the South East, which reports on 1 July, will fail to settle the crucial issue of whether Heathrow or Gatwick should expand.

The long-awaited blueprint from the Airports Commission, chaired by Sir Howard Davies, is expected to give its seal of approval for expansion at Heathrow provided there are proper safeguards on air quality, carbon emissions and noise. But it is also likely to keep alive the option of building a second runway at Gatwick.

The emotive question of extra capacity has dogged successive governments since 1971. The Coalition, which set up the Davies Commission in 2012, hoped the review would get the Government off the hook by coming down for either Heathrow or Gatwick. But Whitehall insiders expect it to “pass the parcel” back to ministers in what would be seen as a fudge.

The Commission shortlisted three options: an £18.6bn third runway at Heathrow; extending the northern runway at Heathrow at a cost of £13.5bn and a £9.3bn second runway at Gatwick.

Airports Commission chairman Sir Howard Davies (PA)

Its final report was delivered to the Government on 30 June and has been kept under strict wraps. Patrick McLoughlin, the Transport Secretary, will make a Commons statement on the commission’s findings but will say the Government needs to take time to study it thoroughly and so will not make a decision before the autumn.

Although George Osborne is thought to back Heathrow’s expansion, there is growing speculation among MPs that David Cameron may seize on the Gatwick option. The Prime Minister is said to be reluctant to break his pledge in 2010, when he said: “No ifs, no buts, there will be no Heathrow expansion.” Although the Heathrow scheme has changed since, backing it would provoke claims of a U-turn and a broken promise that some allies fear could haunt him like Nick Clegg’s on university tuition fees.

Another reason for caution on Heathrow is opposition from senior Conservatives. Five Cabinet ministers represent constituencies which would be affected by expansion at Heathrow and are opposing the plan. They are Theresa May, the Home Secretary; Philip Hammond, the Foreign Secretary; Justine Greening, the International Development Secretary; Greg Hands, the Chief Treasury Secretary and Theresa Villiers, the Northern Ireland Secretary.

Boris Johnson, the Mayor of London who is now MP for Uxbridge and South Ruislip close to Heathrow, has threatened to lie down in front of the bulldozers to prevent a third runway. He said: “I remain of the very firm belief that Heathrow expansion in any form is undeliverable and we will have to wait to see what Sir Howard says. I think Howard has been given a very difficult task. I am sure he has done it very thoroughly but obviously it is an extremely difficult problem.”

However, eight Tory MPs representing seats near Gatwick vehemently oppose a second runway there at the West Sussex airport. They accused Cabinet ministers fighting the Heathrow scheme of having a potential conflict of interest in the Government’s decision.

Crispin Blunt, a former minister and MP for Reigate, has accused Sir Jeremy Heywood, the Cabinet Secretary, of failing to implement properly the rulebook on ministers’ conduct. Mr Blunt argues that the Cabinet members with a constituency interest should not take part in a national decision on airport capacity. But Sir Jeremy told him in a letter that the conflict of interest rules apply to decisions taken by a minister’s own department.

Mr Blunt said this interpretation was “risible” and could “significantly prejudice the national interest.” He warned: “The existence of explicit and expressed constituency interests of senior members of the Government is a matter of record. So much so that part of the case being made by the promoters of development at Gatwick rather than Heathrow is the existence of these interests rather than the national interest. It disgraces basic tenets of transparent and good governance that these suggestions can be made.”

Opponents of expansion could take legal action in an attempt to block the Government’s eventual decision. John Stewart, chairman of residents' group Hacan which opposes growth at Heathrow, said: "Even if Davies recommends a third runway, there is no guarantee the Government will go for it as there are so many 'big beasts' in the Cabinet opposed to it. A Davies recommendation for Gatwick could mean curtains for Heathrow as the Government is likely to see it as the more politically deliverable option.”