This is really interesting, especially Warmandfuzzy's comment about them needing to be stretched or ending up dropping out.
That's pretty much what the head of ds's secondary said to us at his interview this week. Basically that he is gifted, but his current school have failed to recognise the fact and properly engage and stretch him. I was gobsmacked really, as I'd read stuff about 'twice exceptional' kids a couple of years back when he WISC results came back and felt it applied to him, but the school was pushing back the other way and telling me I was expecting too much of him and stupidly I believed them and felt I was being unfair to him.

The head said pretty much what Mareeya said able, that once pupils like ds are properly supported and engaged they can take off and soar in their achievement, but if you ignore the lower spikes on their profile then they can't be expected to demonstrate the higher ones to proper effect.
I strongly suspect ds was on the G&T reg at primary throughout his infant years, as he was top of the top set without even trying, but the school has a policy of not sharing that information with the pupils or their parents. When he hit year 3 and started to struggle with anxiety and social skills everything went to pieces and his progress pretty much stalled at that point.
All that's holding him back in maths is his adamant refusal to do jottings/note-taking and his teacher told me at parent's evening that she doesn't bother discussing how he might better understand character motivation and emotion etc in literacy,"because, well, we know he can't do that don't we".
She actually said, "I would probably discuss it with another pupil, give some examples and expect them to go away and think about it, but with ds1 there's not much point".
As a result, the rest of his literacy group are being coached for level 6 sats and he isn't even allowed to attend the sessions
. Mind you, the fact that the sessions are with teachers from the Academy that refused to take him might also have more than a little to do with it. 