MI6

MI6, aka SIS (Secret Intelligence Service), was a branch of the British government concerned with foreign intelligence. Like its domestic counterpart MI5, it was sometimes simply called the Secret Service. Kim Philby explained to the Doctor that despite the fact the two organisations were theoretically working on the same side in two separate spheres, MI6 and MI5 frequently clashed. (EDA: Endgame) On another occasion, the Doctor told Leighton Woodrow he had believed that MI6 had no jurisdiction within Britain's borders, a belief that Woodrow found refreshingly naive. (DWM: The Fallen)