Getting bored wth this now so AP818 Ch 1 refers:
23. On occasions when the Royal Air Force Ensign is being hoisted or lowered at a Royal Air Force establishment all ranks within view of the ensign or within hearing of the Alert call (whistle) are to face the flagstaff and stand to attention, officers only are to salute. These general rules are to be applied by the Air Training Corps in relation to their Corps' ensign.
Jayand, I guess a nasty SWO frightened you at some point?