The Special Investigation Branch (SIB) is the name given to the detective branches of all four British military police arms: the Royal Navy Regulating Branch, Royal Marines Police, Royal Military Police and Royal Air Force Police. It is most closely associated with the Royal Military Police, which has the biggest SIB. The SIBs usually operate in plain clothes, although they may wear uniform when serving overseas. All members are senior non-commissioned officers (sergeants or petty officers or above) or commissioned officers.

Although an SIB appears to have existed in the British Army of the Rhine in Germany between 1919 and 1926, the origins of the army's SIB are really in 1940, when twenty Scotland Yard detectives were enlisted in the Corps of Military Police to deal with the pilfering of military stores within the British Expeditionary Force in France. The unit was formed on the recommendations of Detective Chief Inspector George Hatherill (who later went on to investigate John Reginald Christie, John George Haigh and the Great Train Robbery) and command was given to Detective Superintendent Clarence Campion, head of Scotland Yard's Criminal Record Office , who was commissioned as a major. Campion was hit in the head by shrapnel during the Dunkirk evacuation and died on 20 May 1940, the only SIB casualty of the BEF. After this beginning, the SIB was established on a full-time basis.

The RMP SIB now consists of about two hundred personnel, including Scenes of Crime Officers and forensic technicians. It is divided into numbered units called Sections (for instance, 33 Section SIB RMP), which are subdivided into Detachments, each usually commanded by a Warrant Officer Class 2. There is a section or detachment on most major British Army stations . There is also a Territorial Army section, made up entirely of people who are CID officers in civilian police forces during their everyday lives. The Headquarters SIB RMP is at Campion Lines in Bulford , Wiltshire. Within the RMP, SIB is known as 'the Branch'.

See also

• Redcap (TV Series)