As of January 2018, Labour had 552,000 members, compared to 124,000 Conservative members reported in March 2018. As of April 2018, SNP had 118,000, Liberal Democrats 101,000, Green Party 41,000, UKIP 21,000 and Plaid Cymru 8,000 members. Party membership has risen notably since 2013, both in total and as a percentage of the electorate.Jump to full report >>
Comparing party membership between political parties can sometimes be difficult. Political parties are under no legal obligation to publish membership statistics. There's 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're 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.
The latest available estimates from political parties’ head offices, press releases and media outputs indicate that:
Membership of the Conservative, Labour and the Liberal Democrat parties has increased to around 1.6% of the electorate in 2018, 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 2018.
In April 2018, SNP membership was around 118,000, compared to 25,000 in December 2013; across Scotland, assuming all Scottish National Party members are in Scotland, SNP membership increased from 0.6% of the electorate in 2013 to 3.0% in 2017 and 2018. In April 2018, the Green Party (England and Wales) membership was around 41,100, compared to 13,800 in December 2013. UKIP’s membership increased from 32,000 in December 2013 to around 42,200 in December 2014, though has since fallen to around 21,200 in April 2018.
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 on 31 December 2016:
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 of non-party political organisations including trade unions, charities and campaigns.
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.
 James Tapsfield, Has Corbyn peaked? Labour membership falls by more than 4,200 in a WEEK - but still stands at 552,000, Daily Mail, 30 January 2018
 Data reported at Conservative Party Spring forum on 17 March 2018 and confirmed by party headquarters
 Information provided by the Party’s head office.
Commons Briefing papers SN05125
Authors: Lukas Audickas; Noel Dempsey; Richard Keen
Topic: Political parties