I thought DS2 would be a bit like that, tbh. He's young for his age, quite short and a little bit babyish at times. He is as innocent as the day is long; at 13 (this month) his favourite toy (other than Minecraft!) -is Lego. He needed a year's KMcG to get a '4' in his KS2 English SATS (though got 5s in the others, as did most of his school mates). His spoken English is still very unsophisticated and basic, peppered with silly errors. I confess I chose DS1's school based as much on anything that I hoped they'd 'do well' by all their DC, not just the clever ones, hence would 'work' for DS2. I was worried that the lower sets in a more- dare I say- run of the mill comp could not only contain the less able but also the less-arsed, or 'chair-chuckers' as we call them! So I picked a MC school that didn't feel like a GS (Kings) as I didn't want DS2 to have his 'failure' spelled out in a number. I rated DS1 as 'clever enough'.
Roll on 3 1/2 years; DS1, 15, has morphed into Kevin-the-teenager, all attitood, sulks, slammed doors and an apparent refusal to understand it's not me who'll be sitting his GCSEs next year; DS2 is actually doing better than his DB was at the same age (2 year gap) and, in terms of consistent effort, application and enthusiasm, is his tutor's star-pupil. He won't ace a Russell Group uni place but I'm no longer thinking 'apprenticeship' as a first resort for him!
So with the best will in the world, they change, they develop, they infuriate and please! So though I picked what happens to be the 'best academic comp' in the county, DS2 isn't, as stated, eye-wateringly academic yet is flying along as quite an 'average' academic attainer.
None of the 'Winchester' comps- Kings, Westgate, HB, Perrins or Thornden, more or less- do at all badly academically, but we're blessed with such good comps- lots of consultants' DC go- that they do seem to be able to help all DC along.