One recalls when the first direct entry AQM crewmen arrived at the secret Hampshire Helicopter Base in the early 70s (?) to join the aged M Sigs, M Engs etc.
Known as the "Quartermaster Experiment" (geddit?
) they were mostly scarce-bearded youths. Allegedly, one of their number could not be served at the bar in the Sgts' Mess as he was not yet 18.
I can't confirm that one, but there WAS definitely a sign at the bar:
"Aircrew Acting Sergeants only served if Accompanied by an Adult"