Colonel Valentine Patrick Terrell Vivian CMG CBE (March 17, 1886–April 15, 1969) was the vice-chief of the SIS or MI6 and the first head of its counterespionage unit, Section V. Vivian, while he was attempting to introduce new blood into the service, selected Kim Philby, who later became notorious as "The Third Man" double agent and defected to the Russians, causing considerable harm to the system he had infiltrated.

[4] He was senior superintendent of police for the Delhi province and in October 1914 became an assistant director of central intelligence (Simla).

Between 1925 and 1931, organisational rivalries proliferated among Vivian's CE section, the domestic intelligence agency, MI5, and Scotland Yard.

In 1930, after a series of meetings of the Special Services Committee, the Casuals were transferred to MI5, where they became "M Section"; many still provided the SIS with information.

He was particularly responsible for liaison with MI5 to ensure the legality of the body (SIS were not supposed to operate within the UK).