Just to reassure anyone worried about grades or thinking it may be a bit of a 'lottery'.
I think whilst the majority of applicants will have 6 or more A*s. many do get places with less if they can demonstrate they have something to offer.
From experience we were incredibly impressed with the information provided on Cambridge and college websites and by speaking to admissions people at Cambridge so please use that rather than take what schools say as read. Some dc can be mislead either by teachers not in the know or worse by teachers who think things still operate as they did when they went there !!
Lastly again from experience Cambridge (and presumably Oxford too) admissions tutors are incredibly diligent and professional and select based on a combination of actual results, predicted results, admissions test. reference. PS, supplementary statement, submitted work and interview (remembering that there are usually at least three interviews not just one.)
They know what they are looking for and have years of experience looking for it and we were at least confident at the end of the process that it had been a fair system. They are looking for people who excel in their field, who really want to study that subject in the way that Oxbridge teach it, and who they feel they would enjoy teaching,
sorry for the ramble - I just wanted to dispel some of the myths that its some sort of mystique attached. Clealry courses are oversubscribed and some miss out - those that don't get a place have to be reminded that tutors are selecting from equally good candidates and some miss out by very small margins - but in my experience too some that have missed out are those that just applied because they thought they ought too because of the high grades or the school or parents pushed them too - I think you have to really want it and be able to demonstrate you want it too be successful and that is far more important than how many A stars you got.
And yes they do look at grades compared to the rest of the school - interestingly my DC score on that as the general results at the school are very low (non selective indie with high proportion of SEND) but its a bit unfair as value added is high and I know DS benefits hugely from being there. But I guess that's an exception to the rule - and the benefit is tiny. I think its hilarious that parents think they gain by moving to state sixth from - surely they would gain more by the higher grades the dc might get at a high performing indi ? !