Bare bottom caning DID occur in private (usually boarding) schools in England in the 1970's. I know that for a fact although I agree that there does seem to be a reluctance on the part of those who know this to admit it. It is not fantasy it happened.
Pretty sure it wouldn't have been, that particular head was famed for how hard he caned, and trousers and underpants wouldn't have given much protection. In 40 years of talking to people about their real life school discipline experiences only one said she might have been punished on the bare bottom, and that was at an ultra strict boarding school in Belgium.
The music teacher made a point of slippering two or three lads every lesson, only one or two whacks, but very hard, as we had games straight afterwards I got to see quite a few red bottoms. I remember one day my best mate Malcolm got it and he proudly showed me the tread marks on his bum in the changing rooms!
Same here. Especially the humiliation aspect when after a few swats across their underpants they are ordered to bare their buttocks in front of each other!
It happened to me once at junior school with a few other lads lined up, but really would have liked it at my secondary school with the music teacher who was very good with the plimsoll.