| Northern Ireland Labour Party |
NILP |
Formed 1924. Dissolved 1987. Preceded by the Belfast Labour Party. Succeeded by Labour '87. |
| Official Monster Raving Loony Party |
MRLP |
Formed 16 June 1982. Registered 16 February 2001 (NI), 18 March 1999 (GB). MNIS Party ID 119. Electoral Commission ID PP65 (NI), PP66 (GB). |
| Plaid Cymru |
PC |
Formed 5 August 1925. Registered 14 January 1999. MNIS Party ID 22. Electoral Commission ID PP77. |
| Protestant Unionist Party |
PUP |
Formed 1966. Dissolved 1971. Preceded by Ulster Protestant Action. Succeeded by Democratic Unionist Party. MNIS Party ID 23. |
| Radicals |
R |
|
| Referendum Party |
Ref |
Formed 1994. Dissolved 1997. MNIS Party ID 24. |
| Reform UK |
RUK |
Formed 23 November 2018. Registered 5 February 2019. Formerly known as The Brexit Party (until 6 January 2021). MNIS Party ID 1036. Electoral Commission ID PP7931. |
| Republican Labour Party |
RLP |
Formed 1964. Dissolved 1973. Preceded by the Socialist Republican Party and the Irish Labour Party. MNIS Party ID 25. |
| Respect Party |
Res |
Formed 25 January 2004. Registered 27 February 2004. Dissolved 18 August 2016. MNIS Party ID 26. Electoral Commission ID PP362. |
| Scottish Labour Party |
SLP |
Formed 18 January 1976. Dissolved 1981. |
| Scottish National Party |
SNP |
Formed 7 April 1934. Registered 14 January 1999. Preceded by the National Party of Scotland and Scottish Party (merger). MNIS Party ID 29. Electoral Commission ID 102. |
| Scottish Parliamentary Labour Party |
SPLP |
Formed 25 August 1888. Dissolved 1895. Succeeded by Scottish Labour (part of the UK Labour Party). |
| Scottish Prohibition Party |
SPP |
Formed 1901. Dissolved 1935. |
| Scottish Workers Parliamentary Elections Committee |
SWPEC |
Formed 1899. Dissolved 1909. Later known as Scottish Workers' Representation Committee (1903-). Succeeded by Labour Party (merger). |
| Sinn Féin |
SF |
Formed 28 November 1905. Registered 14 January 1999. MNIS Party ID 30. Electoral Commission ID PP39. |
| Social Democratic and Labour Party |
SDLP |
Formed 21 August 1970. Registered 14 January 1999. Preceded by the Republican Labour Party and the National Democratic Party. MNIS Party ID 31. Electoral Commission ID PP55 (NI). |
| Social Democratic Federation |
SDF |
Formed 1881. Dissolved 1911. Preceded by Manhood Suffrage League. Succeeded by British Socialist Party (merger). |
| Social Democratic Party |
SDP |
Formed 26 March 1981. Dissolved 3 March 1988. Preceded by Labour party (split). Succeeded by the Social Democratic Party (split) and the Liberal Democrats (merger). MNIS Party ID 32. Electoral Commission ID PP243. |
| Speaker |
Spk |
MNIS Party 47. |
| The Brexit Party |
BRX |
Formed 23 November 2018. Registered 5 February 2019. Later known as Reform UK (from 6 January 2021). MNIS Party ID 1006. Electoral Commission ID PP7931. |
| The Northern Party |
NorP |
Formed 2015. Registered 01 April 2015. Dissolved 8 April 2016. MNIS Party ID 180. Electoral Commission ID PP2664. |
| The Reclaim Party |
RP |
Registered 13/03/2019. Formerly known as The Brexit Party (before 6 January 2021). MNIS Party ID 1043. Electoral Commission ID PP9050. |
| Trade Unionist and Socialist Coalition |
TUSC |
Formed January 2010. Registered 27 January 2010. MNIS Party ID 157. Electoral Commission ID PP804. |
| Traditional Unionist Voice |
TUV |
Formed 10 October 20007. Registered 10 October 2007. MNIS Party ID 158. Electoral Commission ID PP680. |
| UK Independence Party |
UKIP |
Formed 3 September 1993. Registered 25 February 1999. Preceded by the Anti-Federalist League. MNIS Party ID 35. Electoral Commission ID PP84 (NI), PP85 (GB). |