interesting post I see Loopy is still well ... "Loopy"
My daughter went to oxford after failing her eleven plus and going to a comp a nice middle class comp but still a comp there were 12 people interviewed at her college for E&M of which 3 got places she was the only non private school person (one of the other applicants had asked everyone). She had good GCSE's mostly a*'s and was predicted A*AA which she got. The other 2 students on her degree (that she got on with great both from top private schools) both got A*A*A* in their a levels and she was concerned she was a bit of a duffer, however academically in tutorials apart from being less confident she soon found she was equal indeed she felt she had a big advantage in that she was used to having to learn stuff herself and had been less spoon fed at her school and ended up getting a higher degree than either of the others in the end, so her view was that oxford was smart to not just go by academic achievement but to look at the context in which the academic achievement was reached. Certainly if i was an admission tutor and i had a applicant with a few a*'s (probably 9's now i guess) in GCSE's from a school that had an average achievement of 20% a-c at GCSE and a applicant for a top private school with all a*'s i would look favourably on the first applicant due to environment and therefore the individual focus and self determination that those results implied.
In fact she was told by her tutors that they do indeed look at final degree results correlated to gcse's and a-level results and that state school and particularly not selective state school students achieve better final degree scores than private and selective state school students with the same pre-university results and thus they feel justified in seeing these results in context.