I work around the city and there is on Moorgate - just off London Wall. Sorry - can't remember the name of the shop. I also know there is one on St. James's Street (opposite the Avenue restaurant) near the Ritz... hope that helps.
There is a shop that sells everything to do with smoking, pipes, tobacco etc in Covent Garden - its on the upper level of the main market buildings above the square where the classical buskers perform. Can't remember the name of it though.