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  1. Formed7 October 1909 · (as the Secret Service Bureau)
    MottoRegnum Defende · (Defend the Realm)
    Organisation

    The Security Service comes under the authority of the Home Secretary within the Cabinet. The service is headed by a Director General (DG) at the grade of a Permanent Secretary of the Civil Service, who is dire… See more

    History

    The Security Service is derived from the Secret Service Bureau, founded in 1909, and concentrating originally on the activities of the Imperial German government, as a joint initiative of the Admiralty and the War Office. … See more

    Buildings

    MI5 was based at Watergate House in the Strand from 1912 until 1916, when it moved to larger facilities at 16 Charles Street for the remaining years of the First World War. After the First World War, it relocated to smaller pre… See more

    Directors General of the Security Service

    • 1909–1940: Sir Vernon Kell (born 1873 – d. 1942)
    • 1940–1941: Oswald Allen Harker (born 1886 – d. 1968)
    • 1941–1946: Sir David Petrie (born 1879 – d. 1961)… See more