They Walk Among Us sounds familiar, didn't they used to be one of the main mail order dealers? I also remember names like; Dangerous Visions and Dark They Were and something Eyed??
Dark They Were And Golden Eyed was the first proper comic shop in London, situated in St. Anne's Court in Soho (ironically the same building where Ross and Gambaccini's Top Ten Comics was, in the early 90s). It was the mecca / hangout for what was then a pretty small geek community. It shut its doors in the late 70s, with most of its staff, including a pre-Comic Showcase Paul Hudson, relocating to Forbidden Planet in Denmark Street.
They Walk Among Us was in Richmond - it had back issues but was mainly focused on merchandise and imports. After at least 15 years of trading it got taken over by Biff Averre of Ace Comics and is still very much open for business. Worth checking out if you're in Richmond...it's near the high street.
30th Century Comics is also still going - located on the Lower Richmond Road near Putney Bridge / High Street, it's definitely worth a look as they have a decent back issue selection.
Never heard of this shop, gotta look for it now
30th Century is the only "real" comic shop still in existence in London. Though the owners make me smile. Remind of Mr Neat and Mr Tidy from the Mr Men