LGW has , or at least used to have, the most efficient single-runway ops I have experienced.
Rapid Exits placed so a holding aircraft is released the moment the landing aircraft is clear.
Line up after the landing, gets you in position.
The next traffic is at 3? miles, and cleared to land as the departing rotates. The lander is around 200'.
Not so at MAN, where traffic didn't justify a 2nd runway. I don't think they ever came close to processing at half the rate of LGW.
No blame to ATC for the flow rates...