I remember a mix up with single service discipline acts when I was at Wyton. The crabs Act changed to allow guests in cabins (basically other halves in the block or somebody you picked up at the bop) and allowing Alcohol to be consumed.
The RN Act didn't match it, therefore our AEO (RN Lt) said the matelots couldn't match what their RAF squadron mates were doing. Therefore the 18 year old LAC in the next cabin could drink but a 24 year Killick (me) couldn't.
The Squadron CO (RN Cdr) took the pragmatic approach that as we were on an RAF Base/RAF Squadron we come under their rules.