Sorry but it is not the case that the more that apply from one school statistically more get accepted. Each and every Oxbridge application is determined on its own merits. This year was a good year, last year was less so. It varies year on year and sometimes what looks like a "better year" get fewer offers than a year that doesn't look as good on paper. In the same way often there are "dead certs" who don't get offers and some well you might as well try , it's only one space, who do.
It would however be the case that students who have achieved their place at a school when there were 10 to 1 candidates for each place (who also did well at gcses) would also be of that above discussed "Oxbridge calibre". They don't allocate places on the basis of 5% of places go to X school and so on.
My own son had a minus gcse score for his gsces in his Oxford feedback which were basically 9 x9, 1 x 8 and 1 x 7 because that was below the average for his school. (Subsequently he has been diagnosed with an SpLD which we weren't aware of when applying). From gcse results reported online I assumed he was average. I had not taken into account that many do extra curricular gsces or early entry ones.
I just think this is not the place for a school v school conversation whether private, grammar or indie, in the same way it is not the place for a candidate v candidate comparisons.
That said we all know that our very able Oxbridge calibre kids may have received an offer on another day and it does smart and take a while to come to terms with sometime. Interestingly too we see some students get an Oxbridge offer but fail to get an offer from say Edinburgh, LSE, Durham and the like. It shows how fine the margins are and that the unis are looking for that slight difference.
I am happy in my capacity of the mum of an Oxford reject (and two other non Oxbridge applicants who have been through uni) and in my work capacity to help anyone with any queries they may have going forward. But I am not interested in negativity towards other schools or individuals and I am sorry if that offends people and of course you are entitled to feel disappointed. I haven't said you mustn't.