Getting back to the original post
We have three children, two are preschool and one in a state primary. We live north of Watford and DH is in the top 5% of earners. We live in an area that has really good state provision, DS is at a great state primary, good results and it is a lovely caring school. I hope that the DTs are able to go there too. Later options, we have great grammar schools in the nearby town which would be our preferred option, I haven't looked into those in detail or the other schools, bit young yet. We couldn't afford to send all our children to private schools, I don't work at the moment, but will go back once the DTs go to school, even then I don't think that we could afford £10k - £15k gross per child.
We are in the position that the state provision is really good, if one child doesn't get into the grammar school we would hopefully be in the position to pay for a private school for that child if we felt we needed too. I wouldn't feel comfortable paying for only one child to go private if the others were not able to go to a school that was suited to them, be that an academically focused school or not. Obviously pp have mentionned specific instances where a private school fitted the care and support that one child required, we have friends who are in that position. To do the best for a particular child, that child is in a private school where her brothers are in the state primary that she was out. They are stretching themselves to do so.
Had a wry smile at some of the posters making comments about choosing the size of your family, we didn't expect twins, were aiming for another one and ended up with two. This has completely screwed up our finances for 4 years, I am going to go back to work and hope that we can get them back on track. We have some savings for the children, hoping that these will be for university tuition fees but if required we would use some of these plus earned income to pay for any private school. I'm really hoping that we don't as I would like to have some short haul hols let alone long haul ones.
I don't see any difference between buying a house with an added premium in the catchment area of a 'good' state school and paying to go private, people use their financial clout in different ways. With the former though, you hopefully will have an asset that doesn't lose value (who knows with house prices, changes in schools though).