Why is David Cameron delaying Heathrow expansion?

Read John Kay on the flaws in the case for Heathrow

David Cameron is coming under heavy fire in the press today, after putting off a decision on whether to add a new runway to Heathrow or Gatwick airport until the summer—despite having previously promised an answer by the end of this year. A report from a commission led by Sir Howard Davies has recommended adding a runway to Heathrow. Writing in Prospect, the economist John Kay has questioned the strength of this case. The concerns he raised about the costs to airlines are very similar to those raised by British Airways, who have threatened to end their operations at their airport if the government expands it. 

Speaking on the Today programme just now the Transport Secretary Patrick McCloughlin insisted there was no political motive and said the government was assessing new environmental concerns raised since the Davies commission made its recommendation. He also appeared to relax the deadline further, saying a decision would "hopefully" be made by the summer. So why might the government want to kick this one into the long grass?

Back Zac and crack

The London mayoral election is fast approaching—next May, Londoners will almost certainly elect the Tory Zac Goldsmith or Labour's Sadiq Khan to replace Boris Johnson. Goldsmith is perhaps the highest-profile and most committed opponent of Heathrow expansion in Westminster, and has said that he will resign from his Richmond Park seat if the government decides to build extra capacity there. If Cameron waits until the summer to say he's expanding Heathrow (if that's what he decides), that might not be necessary; if Goldsmith wins, he will stand down from his seat anyway. Even if Goldsmith hadn't made his threat, it wouldn't be desirable to engineer a split between the party leadership and its mayoral candidate so near before an election.

No ifs, no buts

Specific, concrete pledges are dangerous things for a government to make—just look at the ongoing fallout from Theresa May's inability to keep net migration in the "tens of thousands," or Nick Clegg's earnest diatribes against tuition fees before the 2010 general election. David Cameron reportedly fears that expanding Heathrow could be his own "tuition fees moment"—before the 2010 election he pledged not to build a runway there, "no ifs, no buts." Campaigners have not let him forget it since.

Collective responsibility

The Cabinet is split on Heathrow expansion.  Theresa May, the home secretary; Justine Greening, the international development secretary; Greg Hands the chief secretary to the Treasury; and Theresa Villiers, the Northern Ireland secretary are all known to oppose expanding the airport—and all have controversially been left out of a cabinet committee working on the issue. The all-powerful chancellor George Osborne, on the other hand, is reported to be willing to accept the commission's recommendation. When a decision does come, it will herald rather a fraught period in the corridors of power—particularly as Boris Johnson, another opponent of Heathrow expansion, could be in the cabinet by then.

Benefit of the doubt

It isn't all political intrigue and personal campaigns, though—the government says the reason for the delay is that it is reviewing new evidence, and there has indeed been some. Most importantly, the independent, cross-party Environmental Audit Committee has said that before a decision to expand Heathrow is taken, the airport must demonstrate that it can reconcile expansion with legal air pollution limits.