I think schools should start at 8 and finish at 4.30.
Children have lessons until 1.30, with two equal sized breaks for snack and lunch and play. Teachers teach the core subjects of English, maths, and others such as history, geography, and RE in those hours.
The afternoons are taught by specialists. Sports, dance/gymnastics, music, drama, art, design technology and computing. Two chunks of afternoon learning. Older children might have chance to do two lessons of a particular interest or skill in order to specialise/take external exams etc.
Teachers can't leave the school until 4.30 - these are still directed hours. In that time they mark and plan. They also have the opportunity to take children out for pre-learn, or intervention lessons. They lose out on some of the above stuff if this happens, but that's what happens in lots of schools anyway.
At 4.30 there could still be an after school club for those who need it, but everyone eats breakfast at school. That's part of primary school learning - communal eating. Also at 4.30 onwards there could be more specialist club type interests run, or even Cubs/Brownies/Scouts run from the school too.
Children go home at 4.30 or 6pm having had good subject teaching by teachers and by specialists. The focus on the arts and sports in the afternoon encourages interests in those things for continuing outside school. If things like extra dance lessons or Scouts or whatever ran from 5 - 6pm, that would also free up evening time at home.
Teachers focus properly on the stuff they are confident in. They can choose to teach some of the afternoon subjects if they want/are specialists. They get their marking and planning done in the school day, they take less work home and are more on it for the next day.
Parents don't have to worry about childcare around school hours so much. Families get their evenings freed up a bit.
What do you reckon? Should I be Secretary of State for Education?