This is a good story but thoroughly unsurprising.
Many private schools limit the number of AS and A-Levels they allow their pupils to do to improve stats, so the number of UCAS points isn't a good indicator of quality.
I'd be interested to see the percentages of grammar/private school students who get into Oxbridge universities.
I was educated privately from kindergarten to sixteen and then grammar for sixth form.
Grammar was actually the better education, less emphasis was put on how things looked - more on performance.
I'm not at all surprised that grammars have 'won'.
I go to a private school, and I'm not surprised - it's based around good stats, so there is no room for expansion from students... and you can get even if you're a thick tosser if your parents have enough money...
I'm not surprised to be honest.