This paper presents party membership data published by the Electoral Commission together with the latest estimates from political parties’ head offices, press releases, media reports and academic studies. It will be updated as further information on party membership levels becomes available.

Analysing party membership

Comparing party membership between political parties can sometimes be difficult. Political parties are under no legal obligation to publish membership statistics. There is also no uniformly recognised definition of membership, nor is there an established method or body to monitor it. Nonetheless, the majority of main parties voluntarily include membership figures in annual accounts for the year ending 31 December, submitted to the Electoral Commission.

Although all parties are required to submit these annual accounts by the Political Parties, Elections and Referendums Act (2000), they are not obliged to include membership data. When annual accounts do include these figures, they’re probably the most reliable estimates available.

Data provided on request from party head offices to the House of Commons Library is an alternative reliable source of information. It is used for the latest estimates when possible.

Latest data on party membership

Estimates from political parties’ head offices, press releases and media reports indicate that:

The Labour Party has around 485,000 members, according to estimates published by Politics Home in July 2019.

has around 485,000 members, according to estimates published by Politics Home in July 2019. The Conservative Party has 180,000 members as of July 2019 (Party Chairman Tweet)

has 180,000 members as of July 2019 (Party Chairman Tweet) The SNP had 125,534 members, as of December 2018 (Electoral Commission data)

had 125,534 members, as of December 2018 (Electoral Commission data) The Liberal Democrat Party has around 115,000 members, as of August 2019 (Federal Board Member)

has around 115,000 members, as of August 2019 (Federal Board Member) The Green Party (England and Wales) has 48,500 members, as of July 2019 (Party Head Office)

(England and Wales) has 48,500 members, as of July 2019 (Party Head Office) UKIP has around 29,000 members, as of April 2019 [Party Leader statement]

has around 29,000 members, as of April 2019 [Party Leader statement] Plaid Cymru has around 10,000 members, as of October 2018 [Party statement]

The latest available data suggests that in 2019 the Conservative Party is the second-largest in the UK, having fallen behind that of the SNP in 2018 (assuming that SNP party membership has not increased greatly since 2018). In 2018, SNP party membership rose from 118,162 (April) to 125,482 (August), according to information provided by the party headquarters.

Membership as proportion of electorate

Membership of the Conservative, Labour and the Liberal Democrat parties has increased to around 1.7% of the electorate in 2019, compared to a historic low of 0.8% in 2013. Across the UK, the Labour Party’s membership increased from 0.4% in 2013 to 1.2% in 2017, before falling to an estimated 1.1% in April 2018. Across Scotland, assuming all Scottish National Party members are in Scotland, SNP membership increased from 0.6% of the electorate in 2013 to around 3% in 2018.

Data published in annual accounts

Political parties are under no legal obligation to publish membership statistics. Many parties provide party membership figures for the year ending 31 December in annual accounts submitted to the Electoral Commission. The latest estimates released by the Electoral Commission shows that in December 2018:

The Labour Party had 518,659 members, a fall from 564,443 in December 2017.

had 518,659 members, a fall from 564,443 in December 2017. The Scottish National Party had 125,534, a rise from the 118,162 reported in April 2018.

had 125,534, a rise from the 118,162 reported in April 2018. The Liberal Democrat Party had around 95,000 members, a fall from the 97,403 members in December 2017.

had around 95,000 members, a fall from the 97,403 members in December 2017. The Green Party (England and Wales) had 38,707 members, a decrease from 42,413 in December 2017.

(England and Wales) had 38,707 members, a decrease from 42,413 in December 2017. UKIP had 26,447 members, compared to 23,280 members reported in December 2017.

had 26,447 members, compared to 23,280 members reported in December 2017. The Conservative Party does not publish data on party membership in annual accounts. The latest estimates for 2019 (180,000), 2018 (124,000) and 2013 (149,000) were acquired from public sources and information from CCHQ.

Academic research on party members

This paper includes Party Membership Project data. The project is funded by the Economic and Social Research Council and run by Tim Bale, Paul Webb and Monica Poletti – academics from Queen Mary University of London and University of Sussex

Academic surveys suggest that in 2017, more than half of members of the main six parties belonged to a higher (ABC1) social grade. The highest rates of ABC1 members were among the Liberal Democrats and the Conservatives, the lowest among UKIP and SNP members. Fewer than half of all members were women and fewer than six percent have ever stood for an office within a party organisation.

Data sources

This note uses a range of sources to examine party membership and support in the UK, specifically membership levels and the social characteristics of party members. For context, it also provides data on membership to non-party political organisations including trade unions, charities and campaigns.