Special Branch is not a single unit but a network of specialist units. Each UK police force has a Special Branch, which can vary considerably in size.
Originally, Special Branch had a number of responsibilities:
- Diplomatic, VIP and royalty protection.
- Monitoring of political groups, with a view to advising on public order or other related issues.
- Monitoring Irish support groups, particularly paramilitary activities.
- Dealing with nationalisation issues
- Security at ports and airports
They worked closely with the Security Service and are generally considered to have had a political policing nature. They were noted for sending plain-clothes officers to monitor political and trade union activities, or for recruiting informers within those groups. This led to the creation of a vast collection of intelligence, known as the Special Branch Registry. Special Branch also ran technical units such as photographic or surveillance as part of their intelligence-gathering functions.
Though nominally under the command of their Chief Constable, most regional Special Branches took considerable lead from the Security Service or the Metropolitan Police Special Branch (MPSB), and formed an independent network. Nationally, they coordinated through the Association of Chief Police Officers’ Terrorism and Allied Matters Committee (ACPO TAM). The MPSB was the largest Special Branch and held national functions as a result, for instance the investigation of Irish paramilitary groups.
Every decade or so, the Home Office and policing organisations released ‘Guidelines for Special Branches’, which set out the functions of Special Branches and where they sat in the national security arena.
When computerisation came in, the National Special Branch Information System (NSBIS) was created to network the different Special Branches and store information on political activities of target groups. This included the National Domestic Extremism Database.
Since the early 2000s there have been reorganisations of the Special Branch and its functions, particularly in light of the ‘CONTEST’ counter-terrorism strategy.
The MPSB became part of SO15 Counter-Terrorism Command, which incorporated the Metropolitan Police’s domestic extremism units. Many of the regional Special Branches became part of regional Counter Terrorism or Counter Terrorism Intelligence Units, which also incorporated the monitoring of what was considered domestic extremism. National Special Branch functions became part of government programmes such as PREVENT, PROTECT, etc.