Fferny1 I went to a posh public school for sixth form late eighties. The teachers Oxbridge colleges were listed in our school diaries. The staff chose the Oxbridge pupil set right at the start and they had weekly lessons on how to get in. It was very much a prestigious group to get into. I overheard one of the teachers chatting to his professor friend on the phone about the group and which college for a particular student. It was all very tactical. Great fanfare for those who got in and utter devastation for the very few that didn’t. Pupils knew whose parents and siblings had gone to which colleges. On the odd parent event, parents would be wearing college colours and the school staff would wear their college gowns. It was a big network thing.
Contrast this with my DD’s state school. One of her teachers said she was exceptional and to consider Cambridge for her subject in Year 7 so she had it in the back of her mind. In Year 12 the school picked several out to have a talk and all parents could go to another talk to. But she didn’t like the course when she looked round. School didn’t push it. I doubt any parents round here tell each other which universities they went to.
There is a state school in a diverse area of London that is famous for pushing for Oxbridge and gets loads in.
So the reason they all got in was that was what was the goal from a v early age from family, school and themselves. I am not saying it’s good/bad it’s just how it worked.