School suitable for intelligent boy with Asperger's.

[OneStressBall]

My son is struggling in mainstream and has worked so hard to learn social skills etc. He's top of his year group in Perivale school but has needs related to large groups, sensory issues, etc.
Every Special School I've looked at (I've visited so many) cater to lower/ average academic ability. Is there nothing for highly able/ gifted children? He is 9

Private - not 'Perivale' ?!

Bruern Abbey?

You don't say whereabouts in the country you are, but More House School in Surrey is an independent day/boarding school for boys with average to high intelligence and specific learning difficulties, from year 4 upwards.

Blossom House?

We are in the process of applying for an EHCP. I've no idea whether we will get one.
Private if not too £££ (under £10-15K) but state otherwise. I doubt there's a state/ non specialist setting that can work for him as he can't cope with classes larger than about 18-20 and is far better in small settings. His stress and sensory levels are through the roof in larger settings with more children.
My concern is that specialist settings still don't cater for the brightest children. They say that they do but they don't even offer as many GCSEs or A levels and their expectations of academic attainment are lower.