DS is an academic in one of the universities named. He said that the whole thing is wildly exagerated. There is a small group of posh students who did this, may be a couple of dozen in a university with nearly 20,000 students. It just makes a succulent story for those who indulge in this kind of class prejudice - it can go both ways.
Back in my student days in the 1960s, in a good solid predominantly technically based northern university, we had a similar small coterie of public school boys, all too thick to get into Oxbridge, despite their impeccable education. We had a guy from Eton on our course. Nobody took much notice of them, they weren't relevant even then, they certainly not relevant now, they should be put in a museum.