Best afternoon tea in London?

[KungFuPanda]

I've been to London this week and had afternoon tea at the Mandarin Oriental. More specifically in their Rosebery Room. It was lovely and was a treat for my mum. Good sandwiches, nice warm scones and lots of cakes. Nice and relaxed service too. The kicker for a greedy bugger like me was the opportunity to have more sandwiches and scones when you'd finished your first lot.

So, any other good experiences for afternoon tea in central London?