Just a Spotter.....
What happens if the UK Government decides, "Soddit, there's a recession on and we need more people through our airports". How do they quickly expand capacity at Heathrow? Easy, create something from nothing .... open up the 23:00 - 06:00 period to full ops. No need for a new runway or other expensive infrastructure. OK, plenty of disgruntled locals, but what are they going to do ... riot?
How many new slot pairing would opening up to full 24x7 ops create? What would that do to the price/value of the existing ones?
That would take quite a few years lead time, and I'm only thinking about the extra Air Traffic Control staff that would need to be employed. An extra 20 or so controllers, another 5 Lighting Panel Operators and another 5 Assistants. Training time for an ATCO is about 3 years from scratch, worst case a 50 % success rate (hopefully better than that), so 40 taken on, training capacity at LHR is about 10-15 trainees at a time, so you'd be looking at 4 years, maybe 6 in reality with wastage/retirements/resignations etc.
And that's only the ATC staff, there would be a whole load more issues for BAA Airside Ops etc. Granted, we in ATC perhaps have the longest lead time.
The night jet ban allows the airport to do all of its routine maintenance in that period. On most nights we close off more than half the taxiways for repairs and checks, as well as one of our runways. I'd hate to think about that with more traffic around!