When I took my A levels back in 1982, we didn't get given percentages anyway - that's a fairly recent thing. We just knew the basic mark ranges that I outlined above. 70% was an A because it was hard to get70%. Most pupils took 3 or 4 A levels - I started by taking 4 subjects, but it proved too much for me and I had to drop one. A friend of mine achieved 3 As at A level, and he was an exceptional student. He won a scholarship to Oxford, then to McGill in Canada and was a "high-flyer" at the Foreign Office when he left university. To get 4 As, you'd pretty much have to have been a genius.
Now, because of the modular nature of the exams, it's possible for kids to take 5 A levels and get something like 2 As and 3 Bs. I'm not saying the kids haven't worked hard - they probably have; the problem is that the bar has been set lower and employers and universities know it.