The Social Democratic Party of England is a social-democratic political party in England, and the main centre-left party. It has been led since 2017 by ______.
Social Democratic Party logo

SDP logo since 2006

Founded in 1888, it is the second oldest political party in England after the Liberal Party. In the 1920s it displaced the Liberal Party to become the main opposition to the Conservative Party. Since the 1930s it has been the main rival to the National Party.

The Social Democrats have been in power on several occasions, 1929-1932, 1945-51, 1969-77, 1982-1990 and 2008-2014.

Internationally the SDP is affiliated to the Alliance of Socialists and Progressives.


Early Years

Several socialist, trade unionist and reformist movements had been active during the 19th century. Most notable was the Socialist League, which even contested some by-elections in the 1870s. The Social Democratic Party was founded in 1888 as a merger between several of these groups.

Wainwright Government 1929-1932

On May 20th 1929 Harry Wainwright became the first Social Democrat Prime Minister of England. The Wainwright government passed a raft of social legislation during its first few months in office, expanding the welfare state. Most notable were the Old Age Pensions Act and the Unemployment Insurance Act. The Industrial Relations Act 1929

Harry Wainwright, the first Social Democrat Prime Minister 1929-32

enhanced industrial democracy. Further ambitious reforms were proposed, including the provision of universal health insurance and proposals to change the voting system. However, the economic crisis of 1929 resulted in a lack of appetite for such moves. 

The Wainwright government failed to get to grips with the scale of the economic crisis. The scale of mass unemployment made the SDP greatly unpopular, and perceived economic mismanagement saw middle class opinion swing sharply towards the opposition. The government introduced drastic spending cuts in early 1932 in an attempt to deal with a debt crisis, causing open rebellion from backbench SDP MPs and the resignation of several cabinet ministers. At the 1932 election the SDP faced its greatest ever electoral defeat, reduced to only 35 MPs. 

Opposition, 1932-1945

Holt Government, 1945-51

The 1945 election produced a landslide victory for the Social Democrats

Opposition, 1951-69

Following the 1951 defeat the SDP was to spend the next 18 years in opposition. Despite the defeat Ernest Holt remained party leader in opposition, despite leadership challenges in 1952 and 1953. 

The economic prosperity of the 1950s and 60s made the SDP's policies of wealth redistribution, public ownership and its opposition to the Social Market Economy look increasingly irrelevant. At the 1954 election the National Party significantly increased its majority in parliament. After two successive electoral defeats calls for Holt's retirement increased, although he saw off challenge at the 1954 SDP Conference. In February 1955 he retired as leader, being succeeded by Herbert Braithwaite. 

Braithwate  was very much associated with the traditional left wing of the SDP, and was strongly resistant to both internal party reform and changing party policy. The subsequent period became one of the most bitter and divided in the history of the SDP. The October 1956 party conference in Liverpool saw a concerted attempt by reformers within the party to reform the party constitution heavily defeated by the block votes of the trades unions. The 1957 election saw the SDP lose yet more seats, with Braithwaite casting blame on the defeat on "mysterious and disruptive forces" within the party. 

By the late 1950s support for the SDP was limited to working class inner city areas. The new affluent middle class were put off by fears of socialism, and unsupportive of a repeat of the radical and reforming Holt government. Party membership was also to fall, from a high of 1,000,000 in 1949 to a low of 470,000 in 1959. 

In April 1959 Braithwaite died suddenly. John Hackett was elected as his replacement, regarded as the leader of the reformist faction within the parliamentary party

At the 1961 Party Conference in Bristol the SDP adopted the Bristol Declaration, renouncing state socialism and the nationalisation of all industry in favour of Keynesian economics and government control of only the "commanding heights" of the economy (infrastructure, energy, water, coal and steel). The Bristol Declaration saw a clear endorsement of the welfare state, but an acceptance of the social market economy. 

In 1964 Arthur Brown was elected party leader. Aged only 48 he was significantly younger than his predecessors, and brought a new energy to campaigning. 

Brown and Cox Government, 1969-77

The 1969 election saw the SDP return to government after 18 years in opposition. 

Opposition 1977-82

Given the scale of the 1977 defeat, many predicted the SDP would be in opposition for at least a decade. James Cox stayed on as leader in opposition.

At the 1981 Party Conference in Sheffield the party replaced the Bristol Declaration with the Sheffield Declaration, renouncing nationalisation. Instead the party committed itself to defending a "Strong public sector and a strong private sector held in balance within a mixed economy".

Newton and Smith Government, 1982-1990

Opposition 1990-2008

The 1990 election was the greatest defeat for the SDP since 1932, and saw the party reduced to only 163 seats. 

Miller Government 2008-2014

Tony Miller lead the SDP to electoral victory in the 2008 general election.


The SDP was initially founded in 1888 as a Marxist party. However in 1911 the party renounced Marxism and adopted a democratic socialist manifesto. Under the leadership of Harry Wainwright (1918-1933) the party abandoned most radical socialist rhetoric in favour of social reform, and indeed when the SDP formed a government in 1929 they did not embark on a widespread programme of nationalisation.

The post war Holt government did go through with a major nationalisation programme, bringing the railways, coal, steel, water and energy industries under central government control.

The Brown government in the 1960s and 1970s focused on social reform, and enhancing the welfare system rather than nationalisation, although did bring several failing companies under government ownership in order to save them from bankruptcy.

In the 1980s under James Newton the SDP endorsed elements of classical liberalism, deregulating the financial sector. The 1981 Sheffield Declaration saw the Social Democrats renounce nationalisation.

The Social Democratic Party is a self described social-democratic and progressive political party, and seeks to achieve social justice within the framework of a free market economy. The Social Democrats are socially liberal. On Foreign Affairs the Social Democrats support continued English membership of the European Community.

Party Structure

Election results

Election Seats +/- % Result Leader
1933 National Victory Harry Wainwright
1936 National Victory Alfred Staines
1939 National Victory Alfred Staines
1942 National Victory Ernest Holt
1945 SDP Victory Ernest Holt
1948 SDP VIctory Ernest Holt
1951 National Victory Ernest Holt
1954 National Victory Ernest Holt
1957 National Victory
1960 National Victory
1963 National Victory
1966 National Victory Arthur Brown
1969 SDP Victory Arthur Brown
1972 SDP VIctory Arthur Brown
1975 SDP Victory Arthur Brown
1977 National Victory James Cox
1980 National Victory James Cox
1982 SDP VIctory James Newton
1984 SDP Victory James Newton
1987 SDP VIctory James Newton
1990 National Victory Tom Smith
1993 National Victory Kevin Meldrew
1996 National Victory Mark Albert
1999 National Victory
2002 National Victory
2005 National Victory
2008 SDP Victory Tony Miller
2011 SDP Victory Tony Miller
2014 National Victory Tony Miller
2017 National Victory


Harry Wainwright 1918-1933

Alfred Staines 1933-1940

Ernest Holt 1940-1955

Herbert Braithwaite 1955-1959


Arthur Brown 1964-1976

James Cox 1976-1980

James Newton 1980-1990

Tom Smith 1990-1991

Kevin Meldrew 1991-1993

Mark Albert 1993-1996

William Jackman 1996-2002

Tony Miller 2006-2014