Interesting subject.
I was chosen to display the RAF Puma in the late 1980s. The display we came up with was seen as "adventurous" and in truth it did stretch the aircraft to its limits. The pilot's manual said aerobatic manoeuvres were prohibited, without giving any further guidance on a definition. I took that to mean no more than 90 degrees of pitch or roll.
The RAF procedure was for the incumbent display pilot to come up with a workable display and for it to be approved first at unit level, then by the station commander, then by the Air Officer Commanding. My display was approved without modification and flown successfully. We had a good, safe season and the display was appreciated by those who saw it.
However, after I moved on, permission for the display was later withdrawn following a tail rotor incident. Permission for a display including similar manoeuvres was re-instated in the early 90s, but another tail rotor incident occurred and as far as I am aware, it has never been flown since.
"lsh", who some times posts here, might have some more info as he was the crewman involved after my time.