Every United Kingdom territorial police force has a special constabulary except the Police Service of Northern Ireland, which has a Reserve constituted on different grounds. However, the Royal Ulster Constabulary (and the previous Royal Irish Constabulary) did have its own Ulster Special Constabulary from 1920 until 1970, when the Reserve was formed. The British Transport Police (a national "special police force") also has a special constabulary. In the Crown dependencies, the Isle of Man Constabulary and the States of Guernsey Police Service also have special constabularies, but the States of Jersey Police does not. Jersey has Honorary Police.
The strength of the special constabulary as of September 2018 in England and Wales was 11,343, -12.3% on the previous year. The number of special constables in Scotland in 2018 was 610. Special constables are not the same as police community support officers (PCSOs), who are employed by police forces to provide operational support to regular officers. Special constables usually work for a minimum number of hours per month (depending on the force – the national minimum is 16 hours), although many do considerably more. Special constables might receive some expenses and allowances from the police service, including a £1,100 "recognition award" in Scotland and some forces in England, but their work is in the main voluntary and unpaid.
Special constables have identical powers to their regular (full-time) colleagues and work alongside them, but most special constabularies in England and Wales have their own organisational structure and grading system, which varies from force to force. Special constabularies are headed by a chief officer. In Scotland, special constables have no separate administrative structure and grading system.