As I understand it, the Childrens Act of 1989 had a huge effect on how these places were run. It took a while for the law to filter out into practice so people who went to private / boarding / posh state schools in the 90s experienced a gradually toned down version.
I suspect that in the early years, when physical punishment was banned, the psychological stuff amped up a bit.
Even at a state school in the 90s, some things we thought were normal would be shocking and absolutely a child protection issue these days.
I was surprised to learn recently that corporal punishment wasn't banned in British state schools until 1987, and in private schools until 1999.
"Surprised" because by 1999 I'd been attending a British private school for several years and corporal punishment certainly didn't exist at my school, or at any school I knew about. Apparently it was permitted on paper though. I'm not sure how common it still was, if it existed at all.
In any case, the worst treatment I received at school was never from the staff and always from the other boys. I can definitely think of some behaviour I saw from pupils back in the day that I'm sure wouldn't be tolerated for a second these days.
In the US, I have relatives that were locked in closets by teachers and had their knuckles rapped for using their left hands.
A combination of factors (cameras and modern communications systems being two significant ones) have shone a lot of light into what used to be very dark corners.
I went to school from in Scotland about 1970 to 1983 - without much difficulty I can think of quite a few situations that I would hope would result in sacking and criminal charges these days.
Being a bright kid and usually "teachers pet" I didn't get too much abuse directly but I can remember one poor guy who clearly had learning difficulties getting his face smashed repeatedly slammed into the blackboard by a teacher - we were about 6 at the time. :-(
I suspect that in the early years, when physical punishment was banned, the psychological stuff amped up a bit.
Even at a state school in the 90s, some things we thought were normal would be shocking and absolutely a child protection issue these days.