I'm 52 so was practically the last year to do Olevels.
I'm currently looking to change my job and feel my age is probably against me. I'm fit and reasonably well presented, I don't think I come across as "old" when you meet me and a lot of applications don't require DOB, but obviously the Olevels give it away.
I know people will say they're irrelevant now, but I find the "essential" criteria often includes maths and English GCSE or equivalent.