What age can a child go home from school alone?

[Elliebelli]

Just wanted to find out at what age does your school allow a child to go home by themselves?

At my DC’s school, it’s the start of the summer term, which I find far too long to wait.

British school, not in UK.
Y2 is dismissed from class to find their own bus (from about 70) in the car park. School of 2000 kids.

Start of Y6 in our school in London Zone 4, parents have to sign a permission slip