It looks like all secondary children bar Y10/12 home until September at the moment.
As a teacher, it's pretty clear the government priority is childcare, not education IMO.
I think there are a few reasons to keep secondary children off, though:
-Lots of secondary children use public transport to get to school and the government is trying to minimise numbers on public transport.
-Lots of secondary children use LA transport and it would be difficult to make this safe for all children.
-Secondary children, in general, can work independently and most of them can stay home alone for longer periods.
-Secondary children who make their own way too and from school might be more likely to visit a friend's house, breaking lockdown (we have actually had this issue with one of the key worker children in school).
-Secondary teachers could be used to help care for primary children.
-There are lots more children in even one year at secondary school, and lots more adults, so more people to potentially infect each other.
I'm not saying this is right or wrong, just the possible logic behind the government decision.
From an educational PoV only, I'd want Y9 and 10 back first, before any primary aged children, but this wouldn't help people return to work much.