The vast majority of children (93% nationally) go to state school. Therefore why should the vast majority of university places not be taken by state school pupils?
Well they are. When it comes to Oxbridge however, things are a little bit different.
But is it really surprising?
No matter how smart you are, if you're studying at say The Ridings: www.independent.co.uk/news/education/education-news/sad-tidings-for-the-ridings-as-school-dubbed-bri tains-worst-is-closed-down-398358.html
you've got fuck all chance of achieving anything other than a criminal record.
A proportion of state school children are destroyed by the system.
Then there are the parents who don't care about education. These kids also have no chance - and they'll all be at state school. Again a minority, but it's another proportion knocked out.
Then there is the fact that private schools have better facilities and smaller class sizes. This will tend to produce better outcomes.
Then there's discipline. Private schools don't have to tolerate bad behaviour. They can kick you out as soon as look at you. It's very well documented that one or two trouble makers can destroy the education of an entire class.
Then there are higher expectations. Many kids are capable of more, but due to a combination of the factors above, they are never stretched. Higher expectations lead to higher achievement.
Finally there's the fact of wealth - and education - begetting the same. You don't, generally speaking, get to be wealthy by sitting on your arse doing nothing. It takes hard work and dedication. So successful parents (i.e. those that can afford school fees) are likely to encourage their children to follow their path. You don't get to Oxbridge without either being very clever, or working very hard, and probably both.
So in fact something would be untoward if Oxbridge admissions were 93% from state schools. The fact that they are not is caused by the factors above.
Also - for most people this is simply a non-argument. Look at what a small percentage it actually relates to. And if you factor out London it's even smaller - here in South Yorkshire it's not 7%, more like 5%, and the affluent suburbanites of Sheffield account for most of that. In Barnsley I believe it's close to 0%.
Well not just London. In Surrey it's about 25%.
The prominence this so-called choice gets on here is nonsensically disproportionate, leading to guilt like that expressed by the OP. You'd think private school was something so germane to the vast majority of children's welfare - like milk, or weaning, or play. In fact, it occupies a minority position on a par with Chicken Keepers.
Well possibly, but this website is clearly not representative of society. Most people don't buy their clothes from Boden or their food from Waitrose (in both cases, too expensive for most), but both are featured heavily here.
This website is not most people, or inner-city Sheffield, it's actually very middle class. And of course if you are a 'worrier', you are far more likely to be on a forum than not. Some people will still worry about this, even if they can't afford it (though affording is in some cases a matter of priorities: I know a single mother nurse in inner-city London who sends her son private. She can't really afford it, but does it because she sees that her friends have children who walk and talk like gangsters, and to her avoiding that is the most important thing in the world.)