MI6 (Secret Intelligence Service)
MI5 (Security Service)
Secret Service Bureau formed 1909
Home Section (Cap.Mansfield Cumming "C")
Foreign Section (Cap. Vernon Kell "K")
during WW1 Foreign Section became MI1(C) and SIS (MI6) 1921
Mansfield Cumming was first Head of MI6 1921-23 ("C")
Home Section became Security Service (MI5) 1931
MI6 took charge of Government Code and Cypher School (GC and CS) 1919
became Government Communications HQ (GCHQ) 1946 (Bletchley Park)
The following are now defunct (all Directorate of Military Intelligence)
MI 1,2,3,4,7,8,9,10,11,12,14,15,16,17,19
MI9 assisted escapees and evaders during WW2
created December 1940 under Colonel Norman Crockatt
A Force created Cairo 1941 for subterfuge and counterintelligence
under Colonel (later Brigadier) Dudley Clarke