Chaz-your school sounds exactly like the one I send my children to and I love it. I agree that some smaller independent schools can be lacking in many areas but I have chosen to send my 3 dc to private school and am lucky enough to (as far as we can predict), carry that through until the are 18.
The argument I don't fully understand is that if there were no private schools, state schools would improve due to the addition of families with money. Surely, in many areas, it would further reduce catchment areas and drive up house prices close to certain schools. So many of the friends we know that are sending their children to private, live in smaller houses than they would like and aren't having fancy holidays or driving flash cars. If they weren't paying school fees, they'd move out to the desirable villages and move their children into the village school. Most of our friends that do send their children to said village schools live in 400k+ houses and their children feel much more of a sense of 'privilege' in terms of material things. (my eldest is only eight so has no awareness of fees)
I don't think I'm being very clear and I fully realise that neither myself or my friends represent the national average but the reality is, if private schools were abolished, society would still split itself up.....
(if it's at all relevant, I was raised on a council estate, went to state catholic schools all the way, relied on my grant and part time jobs to get me through university and spent eight years as a primary school teacher in south London state schools)
I don't know what the answers are but am not convinced that abolishing private schools would help anyone)