This is a positive scenario undoubtedly, but I remain to be convinced that we'll have a drastic halt in the rise of flying, followed by a decline in it. To do this, we'll need to transform how we understand ourselves, our relations to others (and other generations), and the ecosystem on which we rely. A more negative scenario is that the PM has just committed to spewing out more CO2 into the atmosphere with a private jet, himself mimicking the elite entrepreneurs that he serves so well, and that there will be other new, diverse forms of flying that emerge (e.g. Branson's trips to the moon).
I don't think we'll have an immediate halt in the rise of flying though, I think demand will increase over the next 10 years, then slow down and then start declining. My point is that we'd be building Heathrow just about at the time that demand levels off. But I totally agree that we will start examining our relationship to our ecosystem more closely and who knows what will happen in the future. There will be climate change provisions of some sort, maybe a levy on aircraft fuel (something that's been floated from time to time). Maybe the restrictions on night flying will be lifted as we move more to a 24-hour society. Maybe terrorist get hold of more powerful weapons and instead of two terrorist attacks a year, we have two a week, I bet that would affect demand for air travel.
I don't know what will happen exactly, I can't predict the exact future. But I do know this: you can't extrapolate future performance on what's happened in the past as others have done in this thread. Just because airline travel has increased significantly in the last 20 to 30 years, that doesn't mean it will increase significantly in the future. I can just imagine an accountant for a coach company sitting over his Regency spreadsheet in 1810 and saying "Passenger numbers up 18% this year, 15% last and 100% since 1800: I reckon we'll have a 500% increase by 1840". Or, more recently, just ask Blockbuster how an increase in sales helped them grow indefinitely.
And this decision is so obviously related to the mayoral elections.
Now that I totally agree with. And what a sign of cowardice by a weak prime minister