So actually, Endod, what you are calling for is a system which selects the well behaved? And the non-unpleasant? Or to be precise, aims to protect high achievers from unpleasant children?
In your ideal academically selective school, what happens to the diligent, well behaved middle attainers?
"Widening admissions just meant standards fell for everybody and the school became increasingly unpleasant." Can you be specific about how standards fell for everybody? Do you mean the average % of A_C passes went down, or do you actually mean that the high attainers in the school started to do less well and high attainers got fewer GCSE passes, at lower levels, than before?
Or did the demography change? Once it was no longer selective did a certain band of parents decide not to send their children there any more?
I really am interested to know on which Christian philosophy parents who wish for exclusivity in CoE school you describe, or the Catholic schools that look set to jettison lower attainers base their decisions on.
Kent as a county does not, overall, produce better results than counties with non-selective schooling. If a school can't manage a mixed ability intake, then maybe they weren't actually a very good school in the first place, but just reflecting the raw material.
I suspect a ot of schools will be tempted to do this, though, just so the Heads can enjoy the reputation of running a 'good' school, when all the kids are of high ability AND have parents who went the extra mile to get them into a selective school - with all that that entails. preparation, possibly more expensive uniforms, possibly an extra bus fare, maybe even just getting round t filling out the supplementary entrance form.