Not sure how to quote the quote above, but the new coalition in British politics both said, prior to the election, that they did not approve of the third runway. It isn't just 'Greens and Nimbys'.
And with the need to cut the budget deficit in the short-term, there is no way it could go ahead - and neither will the fast rail line, nor any suggestion of relocating Heathrow to the Thames Estuary - in the near future, assuming the state would have to input huge resources at a time when they are cutting what people consider to be vital services such as health and education.
The same problems apply to the Severn Barrage which could generate 10% of Britain's electricity - in the short-term it requires lots of capital which isn't available, and would not show a return for many years, but ultimately be for the nation and the environment's good.
I don't like it - London needs a new/expanded airport - but that's the way it is.