More a case of the uber rich stay rich.
The poor put up with the crappy state schools.
The middle and somewhat rich do everything possible to secure the best state schools, and then supplement with tutors and extra curriculars (and stashing away enough so kids can pick university based on the best course not the cheapest accommodation).
Only now, there are more of that group and because they're now wanting state education not private, that bumps a few others down to the crappy comp.
But hey, we're all equal and using the wonders of the state provision.