House of Commons Library

UK Election Statistics: 1918-2017

Published Thursday, April 27, 2017

This paper presents an overview of election results since 1918. It provides summary results for all elections from 1918 to 2017, focusing on elections to the House of Commons.

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This Commons Library briefing paper presents an overview of election results since 1918. It provides summary results for all elections from 1918 to 2017, focusing on elections to the House of Commons. It also includes elections to the European Parliament, devolved legislatures and local government.

General Elections

The graph below provides data on share of votes by party in the UK General Election from 1918 to 2015. This graph and supporting reference table is available in the Briefing Paper on p. 6.  

Share of the vote by party: UK General Elections, 1918-2015



The Conservative’s best result in terms of seats won since 1945 was at the 1983 General Election, when 397 MPs were elected. Its highest share of the vote was 49.7% in 1955.

At the 1997 General Election, there were 165 Conservative MPs elected and the party received 30.7% of the vote. This was its worst performance in terms of share of the vote and seats won since 1918.


The first Labour majority government was elected in 1945.

The highest share of the vote received by Labour in a general election was 48.8% in 1951, when the Conservatives won the most seats despite polling fewer votes. Labour’s worst general election performance of the post-war years was in 1983, with 27.6% of the vote and 209 seats.

In 1997, Labour's 418 seats were the highest ever number for a single party.

Liberal Democrats

The Liberal Party contested the 1983 and 1987 elections in alliance with the Social Democratic Party (SDP), before the two parties merged in 1988 to form the Liberal Democrat Party. The SDP had been established in January 1981 and by March 1982 it had 29 MPs, most of whom had defected from Labour.

The Alliance received a quarter of votes cast in the 1983 election, but won only 23 seats.

62 Liberal Democrat MPs were elected in 2005, the highest number for the Party and its predecessors since 1923 (when the Liberals won 158 seats). In 2015 the number of Liberal Democrat MPs fell to 8 compared with 57 at the 2010 General Election.

Scottish National Party

The Scottish National Party (SNP) won its first seat at a general election in 1970. Until the most recent 2015 general election, the October 1974 election, when the party received over 30% of the vote in Scotland and won eleven seats, was the SNPs greatest victory. However, in 2015, the SNP won 56 of Scotland’s 59 seats with 50% of the Scottish vote.

Plaid Cymru

Plaid Cymru won its first seats in a general election in February 1974. The most seats won by Plaid Cymru at a general election is four, in 1992, 1997 and 2001.


The UK Independence Party won its first General Election seat in 2015 with 12.6% of votes in the UK, a rise 9.5% compared to 2010. It also came second in 120 constituencies.

Green Party

The Green Party won a House of Commons seat for the first time at a 2010 General Election, this seat (Brighton Pavilion) remained the only Green seat after the 2015 General Election. Although the Green Party did not increase its number of Commons seats at the 2015 General Election, their share of the UK vote increased by 2.8%.

Ulster Unionists

Since Northern Ireland House of Commons (Stormont) was established in 1921 The Ulster Unionists dominated elections to Westminster as well as to the devolved Northern Ireland Parliament. The Ulster Unionists took the Conservative whip at Westminster until 1972. In this paper, Ulster Unionist general election candidates are listed as Conservatives for elections up to 1970 but are listed separately from 1974.

Democratic Unionist Party

The Democratic Unionist Party (DUP) have replaced the Ulster Unionist as the main unionist party in 2001. Having held a majority of Westminster seats in 1997, the Ulster Unionists failed to win a seat in 2010, but secured two in 2015. The DUP currently hold eight seats.

Sinn Féin

Sinn Féin increased its share of the vote at every general election between 1992 and 2010, when they held five seats, in 2015 it reduced to four.

The Social Democratic and Labour Party (SDLP) won three seats at each general election since 1997 although its share of the Northern Ireland vote declined from 24.1% in 1997 to 13.9% in 2015.

Speaker of the House of Commons

The Speaker of the House of Commons now contests general elections as “the Speaker seeking re-election” rather than as a party candidate. By convention the main parties do not put up candidates against the speaker.

In this paper, the Speaker is listed under ‘Other’ for elections from 1997 onwards. For elections before 1997, the Speaker is listed under the party for which he or she was formerly a Member.

Detailed analysis of party performance at the General Election and supporting data is available in the Briefing Pager sections 2.1 to 2.5 (pp. 6-27)

Characteristics of MPs


191 female MPs were elected at the 2015 General Election (29% of all MPs). In total, 557 women have been elected to the House of Commons since 1918, 7% of all MPs over the period.

Section 2.6 (p. 28) in the Briefing Paper includes a table which shows Women MPs elected at General Elections by party 1918-2015


As individual’s ethnicity is self-defined, it is hard to obtain historical records of MPs’ ethnicity. It is generally said that the first black and minority ethnic (BME) MPs since World War II were elected in 1987, when four Labour MPs were from BME backgrounds.

Table 8 (p. 29) in the Briefing Paper shows Black and Minority Ethnic MPs elected at General Elections, 1987-2015

Other characteristics of MPs

Briefing Paper includes information on the following:

House of Commons by-elections

Great Britain

Generally parties in government perform poorly at by-elections while opposition parties have the chance to make gains. In the 2010-15 Parliament the Conservative party lost three of the four by-elections in seats it previously held. There have been eight by-elections since the new parliament was elected in 2015

Table 12 (p. 36) in the Briefing Paper shows a summary of parliamentary by-elections in Great Britain, 1945-2016

Northern Ireland

There were by-elections in Northern Ireland in six of the last nineteen Parliaments (detailed statistics are available in the Table 14a and 14b (p. 38) in the Briefing Paper)

European Parliament elections

Elections to the European Parliament are held every five years. Prior to the first direct elections in June 1979, members of the European Parliament were delegates from national parliaments.

After a change in electoral system in 1999, there was an increase in the number of MEPs from other parties. Ten Liberal Democrats were elected, compared with two in 1994, and the UK Independence Party (UKIP), the Green Party and Plaid Cymru got their first MEPs.

Table 15a (p. 50) in the Briefing paper shows UK MEPs elected at European Parliament elections by party, 1979-2014

Devolved legislatures and London elections

The graph below provides data on the number of members in devolved legislatures and London assembly in the period from 1918 to 2016. This graph and supporting reference table is available in the Briefing Paper section 5, pp. 52-62.  

Members of devolved legislatures and London Assembly 1998-2016:


National Assembly for Wales

Since the establishment of the National Assembly for Wales in 1999 Labour has always had the largest share of Assembly seats. 2016 was the first Assembly election when all three UK-wide parties: Conservative, Labour and Liberal Democrats lost seats.

Table 16 (p. 53) in the Briefing Paper shows National Assembly for Wales elections, 1999-2016

Scottish Parliament

The Scottish National Party have dominated the Scottish Parliament since 2007 when they overtook the Labour Party by one seat. The Conservatives became the second largest party after overtaking Labour by seven seats in 2016.

Table 17 9 (p. 55) in the Briefing Paper shows Scottish Parliament elections, 1999-2011

Northern Ireland Assembly

2017 election was called early due to the resignation of Deputy First Minister Martin McGuinness. The DUP remained the largest party but without enough MLAs to use a "petition of concern". The size of Assembly was reduced from 108 seats to 90.

Table 18 (p. 57) in the Briefing Paper shows Northern Ireland Assembly elections: 1998-2011

London Assembly

Since London Assembly was established in 2000 Labour and Conservative parties have the largest share of Assembly Members. They were also the only two parties that had secured constituency seats. Labour became the largest party after winning 12 seats in the 2012 election and maintained its share in 2016. 

In the four elections held since 2000, only Conservative and Labour Members have been elected on the constituency ballot, with other parties picking up seats from the London-wide list.

Table 20a (p. 58) in the Briefing Paper shows London Assembly seats by party, 2000-2016

Local Elections

Council Elections

The graph below provides data on party affiliation of councillors in the period from 1918 to 2016. This graph and supporting reference table is available in the Briefing Paper section 5, pp. 52-62.  

Party affiliation of councillors since 1973 Great Britain

Mayoral elections

Elections for the Mayor of London have been held every four years since 2000, using the Supplementary Vote system. In 2016 Labour's Sadiq Khan was elected Mayor of London.

Table 21 (p. 60) in the Briefing Paper shows London Mayoral Elections, 2000-2016

Elected mayors currently hold office in 16 local authorities (excluding Greater London). There are nine Labour mayors, one Independent, two Liberal Democrats, one Conservative and three from other parties.

Table 21 (p. 60) in the Briefing Paper shows London Mayoral Elections, 2000-2016

Additional data

Commons Briefing papers CBP-7529

Authors: Oliver Hawkins; Lukas Audickas; Richard Cracknell

Topics: Election results : UK, Elections, Parliament

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