But xenia, this is just more anecdote. Not saying it's not interesting but it doesn't go any way at all to prove the hidden premise in your initial argument - ie. that the 15% of 18-19 year olds who entered HE in x year were also the top 15% in terms of intelligence/academic ability.
If we are doing anecdotes, though, I'll offer a counterpoint from my mum's family. She was one of 8 children, all born between 1930 and the mid 1940s; their dad, my GF, was a farm labourer and the family was poor, especially in the early years of GPs' marriage.
My mum and uncle B were the only ones to pass the 11+. Were they the brightest? They were both intellectually able, but so were other siblings. But they benefited from being the youngest two, not called upon to babysit siblings, and from a less precarious financial situation by the time they were born.
I'm not denying that the 11+ was an agent of social mobility for some young people in, say, the 1940s-'60s, but there were obviously limitations.
My uncle B still had to leave school at 16. GP couldn't support him through 6th form, let alone beyond. He became an accountant eventually - no idea what route to qualification he took, but I know he worked first - and did very well for himself; but he was very intelligent, extremely numerate and literate, and I find it hard to believe he wouldn't have been in the top whatever % of his cohort if there had been an objective way of measuring them at 16.
My mum was the only one who got to even stay on at school beyond 16, and that was because her headmistress literally visited my GP at home and begged them to let mum stay on, offering financial support from the school.
All my aunts and uncles were intelligent, though, and my GP for that matter (they both had to leave school at 13/14). They were, however, all born poor, in a part of the country with few opportunities outside farm work for their class, and that significantly impacted on their educational chances.
This seems so utterly, utterly obvious to me that I can't quite get my head round the idea, xenia, that you honestly believe that the most able young people always miraculously rose to the top and ended up at university in these generations.
The main point that comes across to me from this thread, though, is that we don't need to rely on these kind of anecdotes when looking at more recent history. Raven and DelBocaVista have repeatedly explained that good quality data exists showing that participation in HE is still affected by socio-economic and other factors and doesn't just reflect ability. That's literally the evidential background to the whole thread.
I like reading about other people's experiences and family histories, but surely we can all accept the fundamental difference between anecdote and data - especially if we belong to the top 5% (or whatever!) ;)