Related to the thread about school starting times.
At my senior school, we started at 9am. There was no such thing as a breakfast club; everyone arrived from about 8.45 onwards. There was a really long lunch break, about 1 hr 40m - some kids went home for lunch but also it was a huge school so they probably needed a longer lunch break to allow for several sittings, I don't remember (I always took a packed lunch, and we were allowed to eat outside in good weather). The school afternoon was 2-4, though you might stay later if you were doing an after-school activity - up to 5pm. This was in the 1970s.
As far as I remember, 9am was the standard school starting time across all ages when I was young. And in infant and junior schools, it was a minority of children who stayed for school dinners; we all walked home and back in the middle of the day.
I guess now that SAHMs are so unusual for families with school age children, people need to get to work in the morning and I wonder if that's part of the reason that the school day starts earlier now.