We looked at Westbrook Hay and York House last year when we were deciding to move our son for September.
We chose York House, which DS now LOVES.
His best friend from his old state school moved to Lockers and they are very happy with it for him. His mum said she didn't feel it would be the right school for my DS as they don't push them (at least not in YR 2/3) very much, and I was moving my DS because he was getting away with very lazy behaviour in his old state school.
YHS has given me a completely different child, he is totally motivated by their credits/stars/stripes/badges system (who knew it could be so simple, huh??!) And now WANTS to work hard. I am thrilled with him and the school.
We looked around WBH and had a meeting with HM. I think the facilities at WBH were possibly better than YHS, particularly the outside playing space- they get to play in the "woods" and rockery - my DS thought this was amazing and he was sold on that, after doing a three day stint at the school. But I chose YHS because i thought the staff came across better.
Have you thought about YHS too?
If you haven't already done so then I would go round each school on their open days and book a meeting with HM to get a real feel of what will be right for YOUR child.
HTH