Please read wingnut's heroic contribution in this thread:

http://www.flyertalk.com/forum/showthread.php?t=541044

the definitive FTer's guide to dim sum in London.

Laureate is extremely good - but you'll need to go at a time set for dim sum. Popping in for a dim sum fix on a random evening won't yield much in the way of choice. Dim sum is a lunch time treat here call ahead to be sure and reserve a place - (the place is jam packed with Chinese families on Sundays).