In practice this is absolute bollocks. I was an extremely high ability child in a state comp - the school did absolutely nothing for me despite continued pressure from my parents. I was absolutely miserable, frustrated, depressed and had huge emotional problems from the school and ended up hardly in school at all from 15-18. Absolutely nothing about my experience in that school - and it wasn’t even a sink comp - made any difference to the ethos or teaching of that school. In fact, the teachers were openly hostile to children who were academically ambitious and regarded them as an annoying inconvenience who should know their place.
My daughter is currently testing out within the top 0.5th centile of her cohort in national ability assessment tests (these tests are done across both state and private schools). She has particularly high aptitudes in maths, Latin/languages, music and writing. Our only state option is the local catchment school (we are in a catchment-only area), where they cheerfully admitted to me that not only could they not provide resources for her, but they would have absolutely no intention of doing so (the head actually laughed at the idea). They don’t stream/set, and certainly don’t offer Latin or advanced maths.
Am I supposed to make her go to a school that says it can’t really cater for her, in which she would be as frustrated and bored as she was in her (actually very good) state primary, just for some nebulous idea about it being good for others? They spend most of their time dealing with behavioural problems. There is no pressure from me that is going to make them hire a Latin teacher or offer extension maths. It’s completely mendacious to suggest that would happen. Only changes in national policy do that (and, for anyone who seems to think underfunding is inevitable, there was a flourishing gifted and talented programme in state schools under the last Labour government, including lots of funding for NAGTY, which was cancelled by the coalition/Tory governments as soon as they could. It’s a deliberate political choice not to fund G&T provisions in the state sector, just as much as it is not to fund proper SEND provision).
Parents of kids who are SEND or who need other related kinds of support have a similar experience - no matter how much they ask a school, there won’t be any results because the state sector just isn’t set up for it and parental pressure means nothing. My DD has got a bursary and scholarship to a private school where they actually want her and can actually provide for her, and where there are also quite a lot of kids who have SEND or related needs which the local state schools can’t provide for. But according to all of the self-righteous people in the thread, my daughter is meant to suffer because of their ideological hobbyhorses? Why? Kids like her are going to be the doctors and research scientists of the future who’ll be keeping you alive in your old age. It makes zero sense to punish kids for their parents’ wealth. There’s plenty of inequality out there to tax - starting with property wealth - without breaching the principle that education should not be taxed.