I've been asked why I went to grammar school (because my parents chose it for me, is the obvious answer, but I did have some say in the matter, albeit only at the age of 13 when I wasn't necessarily the best person to ask).
By implication, I am some sort of heinous hypocrite for supporting a divisive intellectualist hegemony when I would deny other parents the Magic Power Of the Wallet.
What I would say is this: don't assume that I (or anyone else, but I can't claim to speak for them) necessarily want to keep the state school system that we currently have in every detail. I would be happy for some form of selection to exist, because this would reinforce and develop the principles which already exist within the state system (yes, they do, actually). Please don't (deliberately) misinterpret this to mean that I want a return to the blunt instrument of the 11-plus, or even widespread re-introduction of ONLY the two options of grammar schools or secondary moderns.
It is disingenuous and mendacious in the extreme to claim that the offering of equality of opportunity in education means "assuming everyone is exactly the same". This is not the underpinning ethos of equality as it relates to gender, age, race or sexuality - the acknowledgement of diversity is a key element of these aspects of legislation. Why, then, should educational opportunity be misunderstood in such a deliberately obtuse manner?
Plus, the idea of the state school system as some sort of sausage factory which produces obedient little clone-drones is a hilarious fallacy, just as the "knife-wielding ASBO kids" cliche is. Both could only be put forward by someone whose experience of the system was at best glancing, and at worst gleaned only from newspaper articles.