But I think there should be some mobility between the grammars and those that go to the 'secondary moderns' - perhaps some 13+ places for the late developers?
This was a system that happened years ago, but would depend on the grammar schools having surplus places. Also, the children in the secondary modern would have to follow more or less the same syllabus at the same level to seamlessly transfer.
There are lots of outstanding comprehensives in the UK but I live in an (admittedly) inner city area and (totally anecdotally), if you have a geeky or outstandingly clever child it is not something to be celebrated as it's another reason they can be picked on/bullied.
If it's any reasussurance, an exceptionally able boy (sadly not DS) in DS's low achieving comprehensive - admittedly in a town too small for an inner city - was treated as a minor celebrity by the other kids.
The white elephant in the room for me is the poverty of aspiration and opportunity for those 10/11 years olds whose parents dont understand the system or can't help. In grammar areas, why not have coaching in the classroom for all of the pupils for 6 months - this would surely level the playing field a bit for the bright children whose parents are unable to help/pay for tutoring etc.
I don't think not paying for extra tutoring (especially in something of no practical use like VR and NVR) actually represents poverty of aspiration. But coaching in the classroom won't actually solve the problem. It is a competition. If you up the ante, you just raise the pass mark. FWIW, a couple of years ago I heard an interview with council rep from Bucks who absolutely insisted that their 11+ could not be coached for.