It was originally created in December 1940 as MI9a, a sub-section of MI9. A year later, in December 1941, it became an independent organisation, though still closely associated with its parent.
MI19 had Combined Services Detailed Interrogation Centres (CSDIC) at Beaconsfield, Wilton Park, and Latimer, as well as a number overseas. Beginning in 1940, MI19 recorded conversations between German officers held comfortably at Trent Park in North London; many important secrets were learned from that effort. MI19 operated an interrogation centre in Kensington Palace Gardens, London, commanded by Lt. Col. Alexander Scotland OBE, known as the "London Cage". It was a subject of persistent reports of torture by the prisoners confined there, which included war crimes suspects from the SS and Gestapo held in the facility after the war.
- Foot, M.R.D; Langley, J.M (1979). MI9: Escape and Evasion 1939–1945. London: Book Club Associates.
- Hoare, Oliver (2000). Camp 020: MI5 and the Nazi Spies—The Official History of MI5's Wartime Interrogation Centre. London: Public Record Office. ISBN 1-903365-08-2.
- Scotland, A.P. (1957). The London Cage. London: Evans Brothers Ltd.
- "Churchill sent MI-19 to find evidence of collaboration". London: BBC News. 20 December 2010. Retrieved 19 November 2012.
- Cobain, Ian (12 November 2005). "The secrets of the London Cage". The Guardian. London. ISSN 0261-3077. OCLC 60623878. Retrieved 19 November 2012.
- Cobain, Ian (17 December 2005). "The interrogation camp that turned prisoners into living skeletons". The Guardian. London. ISSN 0261-3077. OCLC 60623878. Retrieved 19 November 2012.
- Cobain, Ian (3 April 2006). "The postwar photographs that British authorities tried to keep hidden". The Guardian. London. ISSN 0261-3077. OCLC 60623878. Retrieved 19 November 2012.
- "What happened to MI1 - MI4?". MI5—The Security Service. 2012. Retrieved 19 November 2012.