John Sauven: Labour should accept the inevitable: the plan is dead

The case against the third runway

There are now so many hurdles in front of the construction of a third runway that the chances of it being built are about the same as the odds on a donkey finishing the Grand National.

When Geoff Hoon gave the green light for the runway last year, an unnamed cabinet minister told the press: "The problem with the third runway is that our policy is going in one direction while the politics are going in the opposite direction." Well, the politics of pushing for Heathrow expansion just got a lot more messy for any government wanting to Tarmac over the village of Sipson.

Let's get out the crystal ball. In the event that Labour wins an overall majority in May (the bookies don't fancy their chances) and the Government still wants to push ahead with the runway, ministers will now have to go back to the drawing board and conduct a broad consultation on key issues where their case is extremely weak – on climate change, the economics and the issue of road and rail access to a bigger airport.

It's unlikely that any fair consultation considering these issues would conclude that construction is justified, and any attempt by the Government to fix the facts (they have form) would see them back in the High Court. Even if they did surmount the barriers in front of them, there would then have to be another vote in Parliament (if you accept that a precedent was set last year when the now obsolete Heathrow policy was put before MPs). A new parliament will be an even less favourable environment for third runway advocates than the last one, and last year's close vote in favour would surely suffer a reverse.

Rubbing our crystal ball again, what if David Cameron is strolling into No 10 with arms aloft on 7 May? The Tory leader has gone on the record so many times saying he'd scrap the runway that a U-turn was always unlikely. But after the ruling that looks a near impossibility.

The third runway is dead and Labour would do well to accept the inevitable. That's the least they could do for the people of Sipson, whose community has lived under the threat of obliteration for years, and for the sake of defending our fragile climate.

The writer is executive director of Greenpeace UK