Lowenergylightbulb - I agree with what you said about how high-fliers can find themselves 'living down' to standards rather than living up to them, and I have my children in private school, with small class sizes, for that very reason, though, as bright as they are, I don't think any of them (well, maybe one) would qualify as a high-flier.
Having said that, my reasons for wanting to abolish state grammar schools is that surely ALL of our children, whether very bright or not, should have the right to be educated in 'an environment where effort and aspiration are the norm'? Why should only the cleverest children deserve that? I understand all the reasons why a grammar school, in all probability, would suffer less from disruption, poor attention, poor discipline, and peer pressure to under-perform or truant, etc, but I still don't think it's fair to cherry pick students who have greater academic potential to benefit from an all-round better quality learning environment when they already have the upper hand by virtue of being clever! Of course the answer is that those children pay a huge part in creating the environment, it isn't just down to having great teachers (though they do), any more than a 'bad' school is the fault of 'bad' teachers. I hate that assumption. I think most teachers in 'failiing' schools do fanastic, utterly thankless, heroic work in the face of enormous challenges and ridiculous class sizes because of the quality of the 'raw materials' i.e. the pupils they are expected to obtain results from.
Nothing can be done (at this level at least) to change the fact that there are so many children suffering from a poor attitude and abysmal attainment, but why is it that average ability children who want to learn, and want to behave, and aspire to do better, have to put up with the disruption, and the peer pressure to dumb down, whilst your very clever child does not? If your answer is that this can be dealt with in comprehensives by streaming, and by channelling children with educational or behavioural 'issues' into a more appropriate practical and vocational syllabus, and away from those who want to achieve in academia I agree. But I don't see why it should exclude the very brightest. After all, it IS a state education, so surely everyone should be treated equally.