Robin, it's you; how nice!
Interesting to hear you use that expression "The Three Bears". The first time I heard this was when I discovered I was working with a girl who turned out to have been at Hertford - quite a bit younger than me, obviously. (I'd wondered why we seemed to get along so well...) She explained that Miss Morrison had chummed up with that fearsome twosome the Misses Jukes and Wilson. I was amazed.
I'm trying hard to imagine the Haileybury band in the gym. How much more of a suitably crowded ambiance that would have created, as opposed to the School Hall! I suppose by then, you were allowed home clothes? Only thing... the gym did have a particularly characteristic
smell. A smell that couldn't possibly have contributed to Romance.
I hear in my mind's ear, the furious indignation of Nellie, as girls with shoes, not of the plimsoll persuasion, trample on her piles of mats, and imperil the surface of the gym floor, on which sacred surface outdoor shoes are strictly forbidden. Suppose a gang of boys become overexcited and start swinging across the dance floor - on the ropes? Or even breaks into the swimming pool next door?
I do hope she never, never got to hear of this.

Nellie, long gone by then!
Details, please, Robin, more details from the teatime confidences of Mr Upton!
"Baldrick, you wouldn't recognise a cunning plan if it painted itself purple, and danced naked on top of a harpsichord singing "Cunning plans are here again.""