I had a teacher who refused to let me go home after a particularly painful period had made me puke. My mum ended up being called in and gave her a right bollocking
Same teacher but even worse behaviour -
Catholic school with draconian very strict uniform policy.
Boy in my year who's mum died of cancer. We were 13/14. This happened in the summer term
Took a while for her to die so time to get affairs in order. She gave her son her wedding ring, got special permission from all the high ups in the school and church for him to wear it on a chain under his shirt in school.
Wicked teacher had a penchant for confiscating anything she saw fit. She was also head of RE and pastoral lead (so knew about the exempt for this boys dead mothers ring). She dedicated a school mass and assembly to this boys family (he had younger brothers in the school too). Obviously knew the score.
Shortly after, this lad was playing football at lunchtime and the ring had slipped out from under his shirt. This teacher instead of asking him to tuck it in, confiscated it. The boy kicked off so she gave him a detention.
As far as I know, his friend then called the boys dad who came into the school by the second break time.
Her office had a window that opened onto the playground. By the end of the break time, there was a considerable crowd gathered outside the window to listen to the absolute dressing down the boy's widowed father gave to her. I've not heard anyone so furious before or since.
It was the talk of the school for weeks. The teacher apparently didn't confiscate anything for the rest of the year and wasn't back the following year