Oops!! I didn't notice how long ago the thread was started. Nevertheless its an interesting question...!
A few years ago, when I first realised that Ds2 was very able, and then he got a NQT and stopped making progress (so the school was failing him), I did my very best to persuade the school to provide for him.
Very naively, i thought that pointing out the problem and asking nicely would suffice to fix this oversight. How they must have laughed after I left the room! Obviously, as i know now, that wasn't ever going to work. Then I tried looking up some regulation that says schools have to teach all the children and I found the "every child counts" policy which i thought was bound to contain what i was looking for.
It turned out that "Every Child Counts" was a misnomer. It was a policy to help the least able only. Then that was replaced with "No Child Left Behind" which at least said what it wanted in the title, although I am fairly sure that the authors added "and no child allowed to work ahead either" in invisible ink, because that's what these policies have meant in practice.
DS2 leaves primary school soon. I am sad to see my youngest suddenly so grown up, even though he's very happy about it! Mainly though, I'll be glad to leave primary school behind and I hope I am more realistic about what the reality of state secondary school will be, than I was six years ago about primary education.