There is a school for gifted Scientists and Mathematicians in the UK

[SundayNightRoast]

... this place.
www.nexuscsia.co.uk

And it's part of a comprehensive school.

Is the answer to have more specialist maths schools like the ones in Exeter and London? One solution could be to expand them so that specialist maths teachers could go out from them to teach top maths GCSE groups in local schools. Many people who would be good at teaching STEM subjects to enthusiastic learners, may not have the skills to keep order in a class of less enthusiastic learners.
I would like to see the present ones expanded to teach chemistry and biology as well as computing and physics at A level.