An IQ can be estimated actually from a US SAT or ACT test and the age of pupil at the time, these tests are taken by many UK pupils and are so considered by our universities.
What?!
First off, SAT and ACT scores can be HUGELY improved by practice and/or coaching - same as IQ scores.
Second, I'd estimate that about one tenth of one percent of UK university applicants have even heard of those American exams let alone taken them.
Xenia, I'm not saying the parents label their children as amazing brilliant (although lots do), but if they are having their IQs tested and then telling them theirs is in the top one or two per cent and enrolling them in gifted and talented programmes etc etc then that is the message that the kids are getting.
Cortina, agree - intelligence is a combination of so many factors, not just scoring well on logic tests.
onceamai, yes, we're kind of straying off the point aren't we ...
Jerking back to reality, yes, lots of bright children are very happy in very academic, competitive schools. But some aren't and they'll do just as well, probably better, in a more mixed ability school, so long as there's some setting. I would not advocate putting an academically ambitious (I prefer that term to saying very intelligent) child in a generally low achieving school - obviously.