seeker
What do you mean they take more privates (and not of the military kind) and selectives?
If you look at the population as a whole - it is no surprise that privates and selectives would "churn out" more A's. That's what these establishments are SET OUT to do. They select people based on ability and really give them the kind of education that might not be "right" for a less able student. Students attending these are also more likely to choose the traditional subjects - the "facilitating" subjects.
A comprehensive that churns out 98% of A's, in my opinion is not a proper comprehensive... unless of course, they make their students choose subjects where they are likely to get an A - which at times happens to not be traditional subjects, and therefore less likely to get them into a RG uni.
If we get rid of all private schools tomorrow - I can assure you, that the intake would still be similar, because as you, seeker, rightly say... these selective/private schools often take the cream of all students. They would still be the ones more likely to apply to RG unis, and would still b the ones more likely to fill it in numbers. BUT you would no longer have anything to rant about because they are all in a comp. Would you think that things would change if ALL of them went to a comp? If you say, their performance would drastically go down, then that's one hell of a good reason to go private.