The Airports Commission delivers its final report tomorrow. Three long years after setting out to find the “answer” to the UK’s airport expansion woes, Howard Davies unveils his recommendations.

The Commission was launched in 2012 with the aim of solving government inertia and a divided political community, by stating once and for all whether the UK needed greater airports capacity – and if so, where it should be. Three years, and £20m, later, we are finally at the finish line and the report will soon be in the public domain.

And yet by its most important objective the commission could well have already failed. As an exercise in finding a way forward it may achieve nothing at all.

The government will likely receive from Davies a technocratic document making the case for Heathrow expansion. The Commission’s modelling suggests that it would benefit the UK economy by up to £214bn, over £80bn more than the comparative Gatwick assessment; it’ll probably also highlight the fact that planes are becoming quieter as technology advances.

But the local loyalties of a few Tory big beasts will make it almost impossible to implement. Theresa May, Justine Greening and Philip Hammond are among cabinet members whose constituencies would be made noisier by Heathrow expansion; so would that of Boris Johnson. All have pledged to oppose new flightpaths over their constituents, no matter what the recommendations of the Commission.

Source: Airports Commission Discussion Paper 5.

The next mayor of London will also have a big influence over where to expand capacity, and here we see the same local concerns taking hold. Denouncer-in-chief Zac Goldsmith, who represents his party’s best chance for 2016 mayoral election, might well resign from the party before countenancing new flight paths across his current Richmond constituency. Cameron will surely avoid the scenario altogether: to directly provoke senior cabinet members and a Conservative mayor looks like a political folly.

It seems unlikely that a Labour Mayor would push for anything different. Speaking at a recent Centre for London event, one of the frontrunners for the party’s nomination Sadiq Khan came under fire from his fellow contenders for his about-face on airports. Having supported Heathrow expansion as a minister under Gordon Brown, it seems that Khan has woken up to the damage such a stance could do to his London mayoral bid – especially if Zac Goldsmith’s name appears on the ballot.

The fact that Khan chose to declare his position just weeks before the Airports Commission reported illustrates the futility of this technocratic assessment, when set against the sheer bloody-minded politics of it all.

(Incidentally Tessa Jowell, Khan’s big rival for the Labour nomination and another who previously backed Heathrow, has suggested she wants to wait and see what the Commission says. It will be interesting to see whether in this debate she stakes a claim as the pro-business opposition to “Green Tory” Goldsmith.)

The Airports Commission has been tempered by politics since day one. Such is its sensitivity that those with the power to make a decision have done all they can to avoid it, pushing back the final report so as to avoid making it a general election issue. Had the Commission been given teeth to implement its recommendations –and crucially backed by all political parties to do so – then significant progress would have been made. Instead the debate rumbles on and is unlikely to come to a satisfactory conclusion any time soon.

Despite its importance to the whole country the airports debate is dominated by a tiny percentage of the electorate from a corner of London and the South East, and the politicians whom they influence. And those politicians have so much at stake, so much invested in their communities and their careers, that they default to convenient NIMBYism.

The next mayor of London may well win an election by opposing Heathrow expansion – and, if Davies is to be believed, the capital and the rest of the country would be poorer for it.

All the noises to have come from the Commission so far indicates that it will primarily recommend Heathrow expansion. But messy local politics suggests that when spades do eventually break ground it’ll be the pro-Gatwick lobby smiling.

Ed Hickey is external affairs officer at the Centre for London. He tweets as @ed_hick.