The key point in the airports row is, I think, that the technocrats can rule options out but only the politicians can rule them in. For example, the industry, the air traffic controllers, and the transport planners are keen on Heathrow, but it’s politically difficult. On the other hand, the planners, the controllers, and the industry hate Boris Island, but it has to be on-the-table because of the politicians.
The aviation technocrats would be sort-of OK with a fenland/south Midlands project (Cublington, Bedford, Alconbury etc) although the ground transport ones wouldn’t, but the politicians won’t rule it in. The civil service and ATCers like Gatwick and the industry would have it, and the transport planners would probably prefer Stansted but could tolerate Gatwick. But each of those have a political veto attached, although the Gatwick one runs out in 2019.
If you want some really exciting proposals, the parliamentary debate on the 1971 report is a classic; let’s do nothing, and concentrate on vertical take-off airliners, which can land at King’s Cross or in the Surrey Docks! Thanks, Bow Group. Why not build the airport on Thorne Waste, near Doncaster? You could clear customs and immigration in your high-speed train racing northwards on its dedicated LGV. Thanks, south Yorkshire Labour MP! Why not build it at Speke Airport in Liverpool, because transatlantic sea passengers used to get the train from London? Thanks, Eric Heffer (for it is he)! Why not build it near Bristol, because…well, Concorde is being built at Filton, and we’re willing to put up with the noise out of sheer boosterism! Thanks, Brissol MP! Sadly, the MP who suggested developing Ronaldsway on the Isle of Man was joking.
I’ve already come out for a flying airport, as I consider the floating one to be insufficiently ambitious. Giant kite-balloons suspend the structure high over…whereever seems convenient, while also generating electricity. Meanwhile, a fleet of Fairey Rotodynes shuttles passengers and freight from city-centre airports up to the platform. Clearly, I should at least get a hagiographic interview with the Evening Standard out of this.
More seriously, I suspect that the final answer will be “muddle through to 2019 and build at Gatwick”, because this minimises the number of potential vetoes, especially if things can be arranged so as to put the decision-point behind the next election. This implies doing something in the meantime, very probably going mixed-mode at Heathrow and revising the various treaties with the communities round about. This will mean more whoooosh for John McDonnell’s constituents, but it’s not like the Tories care, some more whooosh elsewhere, but also that the Tories can claim to have both not built a third runway at Heathrow and also to have provided more capacity there.