I'd just like to pop in and say that , for many students , mainly in state schools , the opposite of grade inflation can and did apply what with the algorithm, and especially in those low eprformign schools Oxbridge et al want to target.
Although the algorithm was (rightly all round ) scrapped , lots of schools adhered to a notion of it when awarding grades , in fear of what the algorithm would do (and to appear to be trustworthy and obedient : state schools aren't usually daring or maverick!). Only schools know what the outcome would have been for their students if the algorithm had been applied at GCSE (for example, I know in my GCSE class, seven of the students who got sixes would have been given 5s and 4s by us but that is the unusual way round because reasons!)
Example: my DS is at a previously low performing state comp. He had a sacked music teacher. A lovely new one arrived but too late to rescue the class's GCSEs. The situation had been rumbling on for several years so the school had a woeful track record of results. The school awarded my DS a 5 for music. Actually, that was them trying to help him out and I am quite sure the algorithm would have massively pegged back the entire music cohort's results. The rest of his results are one 9 , some 8s and 7s so the 5 is an outlier. In Spanish, again the school's track record is not great. He was always second in that class. the one 9 they felt able to dole out saw him given an 8. In business, he had the misfortune of having the very brightest children in the school in his class : so two 9s in the group, and he got the 8. This was after predicted grades of 9s and full marks in his mock.
I am not bitter and don't think he is Oxbridge material quite, but I did want to point out that not everyone did well out of CAGs.
My school (different school) certainly didn't have 20 pupils with all 9s. Nowhere near it ; might have been one. Perhaps the prior example given of this was one of the schools which chose to ignore ASCL's advice to bear in mind prior results and the algorithm when deciding grades. I was certainly only 'allowed' to give one 9 in my subject which means two kids who could have got them didn't.
Question for experts : does Oxbridge miss out on brilliant specialists by only looking at those with perfect GCSE scores? I know they have to select somehow but back when I applied I had very mediocre maths type results and top results in arts humanities, so not a perfect profile. DS is (allegedly) on track to get maybe two A*s and and A at A level (best scenario) but he has the lurking 5 and 7s for maths /science and Eng Lang (another rank order issue that one , grrr). I am not saying he is the brilliant specialist but I can well believe there are English students with poor maths outcomes and definitely vice versa. All rounders are not necessarily the very best in each subject are they? And, hwo much are outlying results (like that pesky 5) ignored?