It always used to be a retirement age of 55 for up to Group Captain, and 58 for Air Commodore and above, though with the possibility of extension in exceptional circumstances, especially for Specialist Aircrew.
My father joined in '42 (aged 19) and flew ops in WWII, and retired in '78. There must have been some wartime blokes in until at least 1983.
The last wartime Spit pilot in a flying job was a Pole, who flew Devons from Northolt in the late 70s/early 80s.