A top Public School I know had a special relationship with a local Comprehensive School with the aim of improving "views" on both sides. The thing that most struck the comp kids was that the annual fees [then] per pupil in the public school exceeded their parents' annual family incomes. I suspect the quality of teaching was similar in both institutions, certainly very good, and the abilities of pupils was not that different either - also very good - so what was the advantage in the private sector? Getting kids away from their parents and peers for much of the year? You tell me.
R.
Yes, I've heard of similar relationships between public schools and those in the state sector.
There are often bursaries and scholarships available in public schools to help those who cannot afford the fees.
Where the school has an entrance examination then the abilities/potential of the pupils will be higher than in a comprehensive school. Then you have the aspirations of the parents and the home environment: if you're paying thousands of pounds for your child's education you are expecting it to give them an advantage in life through bother higher academic qualifications and extracurricular activities.
From talking with my brother over the years it seems that there are the disruptive minority in every class that makes it more difficult for the others to be taught and to learn. In my experience you just don't get that in a public school.
As for getting kids away from their parents, that's only true of boarding schools and even then only those where you board for the entire term/half-term.
Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E