I'd like to add that it isn't a case of "I got rejected, therefore Universities hate Private Schools".
I know of several people with 4 A grades who were rejected straight out, and I've come across maybe two examples of people from state schools with 1 A who were given offers (there will be more, I'm sure)
There does seem to be a pattern emerging, and I wanted to know there was a reason behind it - or if it was just a (very big) coincidence.