Eldest DS went to private in 1990. 2nd DS in 1992. Then the school was small but very friendly, teachers badly paid, but the children were sat on and parents contacted if there was a problem. Then the parents backed up the school, sometimes a child was expelled for behaviour problems. It was very outdoorsy boarders in dorms.
Fast forward to 2011 when youngest went. What a change, dorms were out not enough privacy, outdoorsy had become risk averse. Still smaller classes. The biggest change was the parents. They minority were unreasonably demanding, rude, aggressive. The cars changed back in the 90`s the cars were pretty ordinary, now we had chelsea tractors, amazing sports cars there was much more £££ evident.
What was interesting was the problem children were sometimes council funded having given up on the state system parents who pushed could get them into private boarding schools for behavioural problems. Now there were always these problems in the past, when you met the parents you could see why. I really believe boarding school saved some of these children.
Your days will be longer if you are expected to do evening duties, but as others said marking less books is a bonus.
As for parents, there are pushy, unpleasant, unreasonable ones across the board. You do need a head of department who will fight your corner. These days at school there is a feed up process you cannot demand to see the head in the first instance.