FDF
not sure what happens if an airport exceeds its movements limit, but imagine there would be fines to pay. LHR has not yet exceeded its limit but is perilously close at 478,000. Guess we’ll find out soon?
I doubt it!! The limit was set so high that the place works (it is regularly reported) at 98/99% of capacity, so they don't need to break the limit as they have all that they want!
If the limit had been set at a level that allowed spare capacity for problems and reduced stacking (saving fuel/time/money)??? But that, of course, would mean the govts of 1980s and 90s actually having a policy about air traffic! We know that they didn't, any more than they had/have a policy for the railways.
Your tally of new airports wheere the old one did not close is MOST instructive and a detailed explanation behind all of those should be compulsory reading for Boris. But, since he doesn't care if the airport is built, he does not have to read anything!