I recently flew from LHR, on the way up the taxi driver mentioned an
11pm curfew for flights.
From the hotel window we could see the operating runway.
It was interesting that after about 22:45 then number of inbound
flights pretty much dried up, supporting a 23:00 shut down, but there
was a queue of flights waiting to take off until pretty much 23:30.
How does this work ? Is there a grace period ? Are there exceptions
etc...