Brambletye is very much the opposite of a "hot house" - its really fab at finding something for every child to excel at, and goes out of its way to foster that. So there are very musical, very artistic, very sporty, very theatrical and very academic children all doing equally well there.
I love the fact that the new headmaster, 1.5 terms in, knows every child by name, and what they are interested in. And the setting is spectacular - fresh air to breathe, acres of grounds to explore - so sailing, riding, tree-climbing and den-building are as much part of the experience as anything else. It's not perfect (perhaps less academic than some of the London preps, not as good with girls sports as boys), but I like it.
There are a few London children, but more at 11+ years. Most children are reasonably local, with some overseas children (we are both locally and London-based, depending on what day of week it is!). But even the local children do some boarding.
Cheam, which someone mentioned upthread, is also very good, albeit a bit more "monied".