Corinna H.
Yelp
Kensington Chimes has hundreds and hundreds of sheet music books, certainly the biggest selection I've come across in such a small shop. Literally, every wall is lined with bookcases where you can find everything from Schubert piano solos to opera vocal scores. In fact, it was named the 'winner of printed sheet music' in 2005/6. So if you can't find what you need here, I doubt you will be able to anywhere else.
The staff are all extremely knowledgeable musicians, but it does tend to get very busy in here so you may have to wait a while before you can grab their attention.
There's also a nice selection of acoustic guitars, music related stationary for all the young budding Wagner's out there, and other bits and bobs. At the moment they have score printed crackers! What every Christmas table needs, ah hem...