Universities generally took the richest, most privileged kids. That isn't the same as ability
Educational advantage maps onto socio-economic advantage from the age of about 3, according to the Sutton Trust (a major charitable research organisation for widening participation in HE).
So much of this thread is anecdata, rather than data.
I started teaching in HE at one of the top universities in the country (the top for my discipline) where I had older colleagues who had a rule of thumb that a First was only awarded to written work which was publishable.
There was some interesting research done in the Department of History at the Other Place in the 1980s, which looked at why the First Class degree awards were dominated by men, when women showed themselves to be just as able throughout their degree studies. What emerged was a set of attitudes about what a First meant: that it wasn't just more of a 2, i but better - academic staff at the time subscribed to a view that a First Class essay or exam (in History) had a totally different quality to it - and that students either had "it" or they didn't. If they had to ask what "it" was, it meant they didn't have "it." And when researchers actually mapped "it" onto work & marks, they found that many of what were seen to be innately "First Class" qualities were as much to do with socialised tendencies in styles of writing, rather than good solid historiography. The "good solid" work was seen as always being 2, i and never possibly ever First Class.
Things have become more sensible - we have published criteria for our grade boundaries, and specific assessment criteria. Students know what they need to do. Some of them pine for Firsts but don't get them. But we are transparent about what it takes, we can help them get there, and we can tell them why they don't get there.
As I said waaaay upthread, it is a perfectly reasonable observation to make that in past years, we were consciously and unconsciously under marking students - and I've explained some of the mechanisms by which this happened.
That older style of examining advantaged rich white boys, indubitably.
And look where rich white boys have got the UK in the last10 years ...