Well, I sent my children to state, even though we could have chosen private.
I just didn't see the need.
But then DC1 started falling more and more behind, at SATS he was almost 2 years behind for literacy. The teacher and I made plans on how to get him to a higher level. But in reality, in a class of 36, he slipped through the net.
So, after a few years, we decided to go private, to give him a chance. If we wouldn't have, the school's expectations of him were just so low, he would never even get a level 4 when he's 11. As I don't feel like "writing him off" yet, we moved him.
We found a good private school, expensive but cheaper than most (2400 a term), non snobby, common sense (school trips to Dorset, rather than exotic unnecessary trips). It is also actually a lot more ethnically diverse than our old CoE school.
Not ALL private schools are about one-up manship. Not all children are equally able. If I had an average child, or a very clever one, I would be happy enough with State, but as he needs a leg up I reckon going from a class of 36 to a class of 15 might make a big difference.
It's nice to have the choice, though I wish it wasn't necessary.