I'd also go for Leisure Games in Finchley. It's not central London by any means but it's only a 5 min walk from Finchley Central Underground Station and it has the best stock of any RPG shop I have been in. I always visit when in London.
The address is 91 Ballards Lane, Finchley.
				
			The address is 91 Ballards Lane, Finchley.
 
				 
 
		 
 
		
 
 
		 
 
		
 
 
		 
 
		 
 
		 
 
		