Londoners: Any place that carries brass instruments?

[Norwegianwood]

Hi

My friend is going to london next week, and he's planning to buy a silent brass mute system. Do you know if there is any shops in london that carries brass instruments, and where they are located?
Thanks in advance, on behalf of my friend....

[Bruce Lindfield]

Denmark Street has a few shops like that - also there's Foote's in Golden Square ,Soho...

Or this one looks promising:

http://www.chappellofbondstreet.co.uk/