American Classics has now moved to Carnaby St area next to Redwing.
Clutch cafe in Great Portland Street and Vintage Showroom in Covent Garden can be interesting and Camden Stables may have something to interest you, particularly at weekends, but all these places demand deep pockets and only you know if that works for you or not. The London markup is alive and well be assured...
What about Rokit, Covent Garden? Real McCoy, American Classics etc aren't really vintage shops. I've bought good stuff from Rokit, nice condition M65s on occasion some lovely 80s choch-chip jackets, that kind of thing.