Leaders of both members of the coalition were unambiguous before the election, flatly ruling out any prospect of a U-turn on the third runway. To break that promise now would be a betrayal too far, and I don’t believe many of the two million or so voters living beneath the flightpath would forgive either party. So far, the government position hasn't actually shifted.

This matters for a number of reasons. First, political promises need to mean something. As William Hague has said, there’s no justification in U-turns unless the facts change significantly. The facts around aviation haven’t changed. If we perform a U-turn, my colleagues - particularly those who are now calling for a U-turn – will struggle at the next election to persuade anyone who’ll listen to them that their manifesto is worth the paper it’s written on. If politicians drop their pledges, then why believe anything they promise?

It also matters because a decision to expand Heathrow would be the wrong decision, on every level, and before casually subjecting some two million people to an aerial bombardment, those clamouring for a third runway would do well to look at the facts.

Despite the scaremongering, it’s worth remembering that Heathrow already has more flights to business destinations than any other airport in Europe: more than the combined total of Charles de Gaulle and Frankfurt. London airports as a whole have the highest number of flights to key markets in Asia, the Middle East, North American and Australasia. More passengers fly in and out of London than any other city in the world. Paris, our nearest competitor, is in fifth place.

We are well-connected, we have ample capacity, and we are starting from a position of strength. The problem is that we don’t use that capacity well. If we want to preserve Heathrow’s hub status, we need to stop clogging it up with point to point flights to places like Cyprus and Greece, which between them account for 87 weekly flights, and which contribute nothing to overall connectivity.

We also need to take measures to prevent operators guarding their slots by flying half-empty planes. Heathrow has terminal capacity for an extra 20 million passengers, and with fuller and, in places, bigger planes, we’d be able to accommodate many more passengers. The government attempted to bring in a "flight tax", which would wholly or partially have replaced Air Passenger Duty. It faced legal obstacles, but with fresh thinking it could, I’m sure, identify alternatives. Some have suggested a "slot tax", for instance.

In addition, we need to encourage a shift from air to rail wherever possible. Every week, there are 78 flights to Brussels, 94 to Manchester, 37 to Newcastle, and 95 to Paris. All of these, and many others, can be reached easily by train. With a better high speed rail network, they will be easier still.

But most importantly, we need to relieve pressure on Heathrow by improving links to other airports. For example, Stansted is massively underused, currently by about 50 per cent, and with proper rail links to the City, it would be the natural place for business flights. There is no reason why we couldn’t facilitate a two-hub approach, with Heathrow catering (broadly speaking) for western-facing flights, and Stansted catering for eastern business flights. The point to point flights that merely clog up Heathrow could be taken care of elsewhere.

Those demanding a third runway are yet to explain why we must have a single mega hub. They have not explained how London is supposed to deal with 25 million extra road passenger journeys each year to and from Heathrow. They haven’t acknowledged the masses of spare capacity that exists in London, which is already serviced by more runways than any other European city bar Paris, which has one more. These and countless other questions are simply left unanswered.

Simply calling on government to double the size of Heathrow is lazy half-thinking by people who ought to know better, but who have been captured by vested interest and are allowing them to do their thinking for them.

Zac Goldsmith is the Conservative MP for Richmond Park and North Kingston