Repton school is a great example of a British school catering to an international community.
My kids love going there. I have quite a few friends who have also brought their kids to Repton after trying out many of the new schools, but the academic progress that Repton displays is hard to find elsewhere.
My Kids go to Repton I think it's a great school. My elder one is 10 and the younger one is 6 and they are both going to Repton since they were 3 years old.
But if you are looking for something more exclusive then their school Foremarke is not too bad either if you are willing to pay a slightly higher price.