Silver,
Without getting into a massive economic debate, the treasury is always pushed from every department to give it more money. There is a long held view in the development arena that the wealthy countries should give 1% of their GDP to developing nations. India may have a space programme, but it also has extensive poverty. I really don't want to drag on with this point, but it needs to be made clear to you as you keep repeating it, and there is no way it can be just cut to pay for this airport. And even if it was, judging by the kind of comments I get when I enter conversations with other people, the NHS would get it long before infrastructure.
Now if you think infrastructure is the way out of a debt crisis, go and look at the top 3 most indebted nations per capita (Japan, St Kitts Nevis, Greece), and I will happily debate the grossly induldgent infrastructure projects each has embarked upon, starting if you like with airports.
So I bring you back to the business case. Paxboy, I saw this as a complete fantasy in the govt 2003 White Paper, although this was by no means the first time a Thames Airport had been proposed. I never took much notice of Boris proposing it, but when Foster came out with his version, it gained a LOT more gravitas.
Foster says he has 'stakeholders' who are interested. Nothing to suggest he has actually got out and talked to airlines, but let's suppose that investors are interested.
Silver, let's go as far as saying that govt will back the road and rail infra (although I find this unlikely) - you like to knock all these other business types (we're actually quite good at retail, we export a huge amount of services, and the City, for all its faults, is still a big earner) - so let's see your business acumen.
Stop trying to put the world to rights, or trying to change foreign policy of a country you don't even live in. Airports might provide transportation, which in turn provides economic benefits, but they must stand or fall on their own merits.
So I ask again, and will keep asking, as you are the one who proposed the airport. This is Kent, not Kobe. How much would you set the PSC at, and how else would you earn revenue?
PS - Paxboy, I'd gladly debate the pros and cons of hs2, see the thread marked 'Eurostar' which went into this terrain, Jetblast might have something too.