Since the founding of the Labour Party in 1900, it has seen a steady number of splits and breakaway factions. Some of the breakaway organisations have thrived as independent parties, some have become defunct, while others have merged back with the parent party or other political parties.
| Year | Party | Status | |
|---|---|---|---|
| 1918 | National Democratic and Labour Party | Merged with the National Liberal Party (UK, 1922) in 1922. | |
| 1918 | Coalition Labour | Dissolved after the 1918 General Elections. | |
| 1931 | National Labour Organisation | Dissolved in 1945. | |
| 1931 | New Party | Became the British Union of Fascists in 1932. | |
| 1940 | Oxford University Democratic Socialist Club | Merged with the Oxford University Labour Club in 1943. | |
| 1949 | Labour Independent Group | Dissolved after the 1950 General Elections. | |
| 1964 | Militant | Now the Socialist Party (England and Wales). | |
| 1972 | Democratic Labour | Merged with the Social Democratic Alliance in 1980. | |
| 1975 | Social Democratic Alliance | Merged with Social Democratic Party in 1981. | |
| 1976 | Scottish Labour Party | Dissolved in 1981. | |
| 1981 | Social Democratic Party (SDP) | Merged with the Liberal Party (UK) in 1988 to create the Liberal Democrats (UK). | |
| 1985 | Moderate Labour Party | Dissolved itself after the 1994 European Parliament Elections. | |
| 1990 | Liverpool 29 | Dissolved itself. | |
| 1995 | Socialist People's Party | Dissolved itself in 2015. | |
| 1996 | Socialist Labour Party | Active[1] | |
| 1997 | Socialist Party (England and Wales) | Active | |
| 1998 | Democratic Labour Party | Dissolved itself in 2016, after its last Councillor, Pete Smith, lost his seat on Walsall Council.[2] | |
| 2019 | Independent Group for Change (Change UK, The Independent Group) | Dissolved itself in December 2019 after the general election. [3] | |
| 2019 | Dissolved itself in December 2019 after the general election. | ||
| 2021 | Breakthrough Party | Active |