Hello,
You are missing something!
Pop the following AIR 27 refs in the the TNA search box:
No.504 Sqn F.541 - AIR 27/1967/14
or ...
http://discovery.nationalarchives.go...ils/r/D8413634
No.616 Sqn F.541 - AIR 27/2126/80
or ...
http://discovery.nationalarchives.go...ils/r/D8417050
Col.