Two and a half years ago, the fledgling romance between the Conservatives and the Liberal Democrats was hitting the rocks.
They were bickering about a runway. Having ditched Labour's plans to expand Heathrow, the pressure was back on ministers to consider growing it again, or if not Heathrow, then another airport in the South East.
Business leaders were queuing up to tell them the country was haemorrhaging billions in lost trade because of a lack of connections to hot economies such as China and India.
In the end, they asked someone independent for a bit of counselling.
Academic and business expert Sir Howard Davies set up a commission to look at the options and was told to report back with a favourite but not until after the general election.
Problem brushed under the carpet.
Until now. Sir Howard is about to name the winner.
Then, the new government must decide whether to go along with him.
There has been lots of arguing over the costs and benefits of the possible options. The data below comes from the Airports Commission.
- £18.6bn: Heathrow's owner wants to build a separate, third runway about two miles north of the two it's already got
- £13.5bn: Heathrow Hub (a private bidder, nothing to do with the airport's owner) wants to double the length of one of the airport's current runways so planes land and take off at the same time
- £9.3bn: Gatwick wants a new runway parallel to its current runway
In a nutshell
The Heathrow schemes create the most jobs and make the most money for the country.
But the Gatwick scheme is better for the local environment, and it should be easier to deliver politically and financially. You pays your money, you takes your choice.
The Airports Commission says it would all make planeloads of cash for the UK, although it does advise some caution over the figures. It says:
- Heathrow would make between £112bn and £211bn
- Heathrow Hub £101bn to £214bn
- Gatwick £42bn to £127bn
They would also generate lots of new jobs by 2050:
- Heathrow: 64,100-108,300
- Heathrow Hub: 54,800-92,900
- Gatwick: 7,900-32,600
The cost to you and me
They might be private deals, but we all pick up some of the tab.
Bigger airports mean more passengers, and they've all got to get there on wider roads, better train services and so on.
Heathrow's third runway scheme involves putting part of the M25 in a tunnel, for example, which isn't cheap.
The commission says:
- Heathrow would cost taxpayers £5.7bn
- Heathrow Hub would cost £6.3bn
- Gatwick would cost £787m
Then there are fares.
To pay for all the work, the airports will charge the airlines significantly more to land.
It's assumed those airlines will pass on some of that extra expense, although it's impossible to say by how much ticket prices might rise.
Both Heathrow schemes say that, as the decades roll by, fewer people will be disturbed by noise because planes are getting quieter and they will be higher as they approach.
The new runways are also a bit further away from London.
Currently, about 760,000 people are affected by Heathrow noise.
And even if the airport is expanded, that figure could drop by 100,000 or so by 2050.
But that would still leave 20 times more people affected by a swollen Heathrow than would be affected by an expanded Gatwick.
This would, of course, be little consolation to those living in nice rural areas on the approach to the West Sussex airport.
Local air quality
Most local airport pollution doesn't come from the aircraft engines - it's from all the cars, trucks, buses and trains that feed the place, plus the airport's own vehicles.
Anyway, Sir Howard says Heathrow's schemes will exceed EU pollutant limits at a few local spots during peak hours.
Heathrow always point out that they are near Britain's busiest bit of motorway anyway and most local pollution is nothing to do with them.
Gatwick is fine, locally.
If the Lib Dems had still been sharing power, there would have been volcanic tension over the issue, especially if the commission picked Heathrow.
Most Lib Dems are against airport expansion.
But, of course, they are not sharing power any more.
There are still plenty of Tories with strong views, though.
London's Mayor, Boris Johnson, who is also the newly elected MP for Uxbridge and South Ruislip, is promising to lie in front of the bulldozers if Heathrow gets the go-ahead.
And Richmond MP Zac Goldsmith told me that he'd still resign and force a by-election if the government picked a west London scheme.
International Development Secretary Justine Greening has campaigned against Heathrow expansion in the past, so it's a given she'd be against it again.
Other big hitters, such as Home Secretary Theresa May in Maidenhead, have constituencies under Heathrow's flight path.
I keep being told that the Chancellor, George Osborne, is pro-Heathrow, but I've never heard him actually say it.
Mr Goldsmith told me he had asked him directly and got a non-committal reply.
But would anyone in the cabinet actually resign over the issue? I'm not sure. Not if there is a guarantee of some kind of respite from the noise.
Expect lots of local opposition whichever scheme is picked, though.
Right now, Heathrow is favourite among the majority of industry types I talk to, but no-one actually knows for sure.
Sir Howard has always said that his job is to pick how we'll all fly in the future, and he pointed out in an earlier report that all of the recent growth has been in the low-cost sector.
That led plenty of people to think that Gatwick was the favourite because it's home to so many low-cost flights.
But a few months ago, Britain's biggest cheap-ticket airline, Easyjet, said it wanted a bigger Heathrow.
My gut instinct, and it's just that, tells me that could be significant.
What happens next?
I'm so sorry, but there's a long way to go yet. The Davies decision is just a recommendation.
After the report, the government is likely to make some kind of statement, but it's not clear yet whether that will commit in principle to Sir Howard's recommendation or just be a "thank you, and we'll let you know". If they fail to give even a hint of their plans, it'll annoy a lot of people.
It's thought ministers will then need to run their own consultation, just a short one, maybe a few weeks, to hedge against legal challenges.
It's worth noting that Mr Osborne has been dropping heavy hints that he wants to get on with it as soon as possible, but it could still be months before we get an official decision.
But even if the politicians race it through as quickly as they can, the legal challenges fail and the next government sticks with the plan, no scheme will be open for another decade.