Some people may leave their hearts in San Francisco, but I left at least 95% of each paycheck in London's record stores when I lived there.  I was poor, but oh, so happy! :)   Enjoy! Lola

Berwick Street in Soho is the place to start:

Sister Ray, Reckless and Selectadisc and a few more shops within a few blocks. Also a good place to shop for fruit, veg and erm, for some reason, sex paraphenalia!

Then over to Rough Trade in Covent Garden.

In Camden, there's a ton up and down the high street.

Head over to Notting Hill and go to the Record and Tape Exchange (3 shops located within a few doors of each other) on the High Street and then wander down to the Portobello Road area for Minus Zero, Intoxica and Rough Trade.

Here's a site with some listings - Not sure how old some of the listings are - I know at least one of the cool indie shops on Hanway Street is gone, but there were two there. At least you'll have some addresses and the nearest tube:

http://www.scaruffi.com/music/usedrec.html#london

Also, in Croydon in South London (about 15 minutes from Victoria station)there is the legendary Beano's: http://www.beanos.co.uk/ - they have one floor that's *just* singles - 7inch and 12 inch - they have over 40,000 in stock.  The place has three floors. Heaven. :)

If you want to make some pilgrimages - there's some great record stores in Oxford, Bath, Brighton and Birmingham.