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At one time, he was a valued resource. Kind of man who could spot patterns in the chatter between suspicious parties. Patterns that could raise flags, save lives.

Arthur Cadogan West was an analyst for the British Intelligence department MI6. He possessed a degree in Political Science and spent four years in the British military.


Season 2[]

Mycroft's MI6 handler, Tim Sherrington, asks Sherlock to work on a case of an ex-MI6 analyst, Arthur West, who has been murdered. Once a valued resource, West became erratic due to being bipolar, was released from MI6 and moved to NYC with his wife, Marion, who he then divorced. Even though retired, he provided MI6 with leads that never panned out. Recently, he insisted he had vital information he'd only provide in person, but was murdered. At the Morgue, it's discovered that his arms are missing. Marion reveals she tattooed numbers on Arthur's arms in infrared ink, doesn't know what the numbers mean and that Arthur was convinced there is a mole in MI6.[1] Sherlock discovers that the numbers are metadata of the location and dates that calls were made to the mole. Mycroft confirms he was at the locations on the dates and Watson realizes Sherrington was as well, that he's the mole and he killed Arthur.[2]

S02E23-Arthur West arms
He said they were important...



  1. Season 2, episode 23: "Art in the Blood"
  2. Season 2, episode 24: "The Grand Experiment"