Okay, here is something deep to discuss.
It appears that a strategy for EVERY player playing in an international hub to start the game by flying to LHR. In MT5, the 'clock' has only been running for a little less than 48 hours. There are already shortages of slots there. It's brutal. This appears to be common for many games now.
It is only a matter of time until no one will play (or should play) in LHR.
Due to curfew, high F and C class demands, and limited slot avail LHR is always the first to fill up--but you already knew this :)
Once city-based demand happens, the F and C demand should, in theory, be spread across all the London airports and eliminate the rush to LHR.
It's evolution, pure and perfect - magic. ;D
Cheers,
Denis