He is a fast/slow 'walker'. [=he walks at a fast/slow pace]
She joined a group of 'walkers' in the neighborhood.
(..) just one night off. Yellow Dragon Circus, in London for one day. It fits. The Tong sent an assassin to England... Dressed as a tightrope walker. Come on, Sherlock, behave! We're looking for a killer who can climb, who can shin up a rope. Where else would you find that level of dexterity? (..)2010 TvShow: Sherlock Title: The Blind Banker Season: 1 Episode 2