In the United Kingdom's 2017 general election, 650 Members of Parliament (MPs) were elected to the House of Commons – one for each parliamentary constituency. A record number of women (208) were elected as MPs.^[1]

Parliament consists of the House of Lords and the elected House of Commons.^[2] The State Opening of Parliament at the Palace of Westminster by Queen Elizabeth II was on 21 June 2017. The subsequent parliamentary session was the longest since the formation of the United Kingdom in 1707, and the longest to sit at Westminster since the Long Parliament in the 17th century.^[3] The second and last parliamentary session however was the shortest since October 1948,^[4] lasting less than a month, from 14 October 2019 until Parliament dissolved at 00:01 on 6 November 2019.^[5]

Notable newcomers to enter the House of Commons in this General Election included future Secretary of State for Scotland Alister Jack and future Scottish Conservative leader Douglas Ross. For the opposition, newcomers included Shadow Chancellor of the Exchequer Anneliese Dodds and future Shadow Secretary of State for Women and Equalities Marsha de Cordova.

The Parliament was marked by extraordinary political turmoil as Governments led by Theresa May and Boris Johnson were unable to win a series of important votes on the issue of Brexit. This left both Parliament and the Government in a prolonged state of deadlock and unable to move forward on the issue. Consequently, there was an unusually high number of defections and suspensions, including the suspension of 21 Conservative MPs in September 2019; 10 of those suspended MPs re-joined the Conservative Party in October 2019. The Parliament was dissolved after MPs passed the Early Parliamentary General Election Act 2019, which bypassed the Fixed-term Parliaments Act 2011 to bring the next election forward to December 2019 from its original scheduled May 2022 date.

Below are graphical representations of the House of Commons showing party strengths directly after the 2017 general election, at important intermediate points, and immediately prior to dissolution. This is not an actual seating plan of the House, which has only five rows of benches on each side, with the government party to the right of the Speaker of the House of Commons and opposition parties to the left, but with room for only around two-thirds of MPs to sit at any one time.

This table shows the number of MPs in each party:

More information Affiliation, Members ...

Affiliation		Members[6]
		At 2017 election	At dissolution	Change
	The Speaker	1	1
Registered parliamentary parties
	Conservative – Gov	317	298	19
	Labour – Opp	262	242	20
	SNP	35	35
	Liberal Democrats	12	20	8
	DUP – C&S	10	10
	Sinn Féin	7	7
	Change UK	—	5	5
	Plaid Cymru	4	4
	Green	1	1
Others
	Independent	1	21	20
	The Independents	—	2	2
	BSJP	—	1	1
	Suspended	—	1	1
	Vacant	—	2	2
Total		650
Voting total		639	637	2
Safe majority		320	319	1
Gov short by		4	22	18
Gov + C&S total		326	307	19
Gov + C&S majority		13	-23	36

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Notes

• For full details of changes during this Parliament, see Defections and suspensions and By-elections.
• Labour, as the largest party not in government, took the role of Official Opposition (OO). The Co-operative Party was represented in the House of Commons by Labour MPs sitting with the Labour and Co-operative designation.^[7]
• "Members elected" refers to the composition resulting from the election on 8 June 2017, but note that the confidence and supply arrangement (C&S) was only reached on 26 June.
• The "voting total" is the effective size of the House excluding vacancies, suspensions, and certain members (ten at dissolution): the Speaker, two (usually three) Deputy Speakers (one Labour and one Conservative) who had only a tie-breaking vote constrained by conventions,^[8] and seven abstentionist members (Sinn Féin). This left relevant party voting totals as follows: Con 297, Lab 241, SF 0, Speaker 0.
• The "safe majority" (the number of seats needed to have a majority of one or two), "Gov short by" (the margin by which the governing Conservatives are short of that majority), and "Gov + C&S total" are based on the voting totals. The government entered into a confidence and supply agreement to secure a small majority, which shrank due to defections, finally disappearing on 3 September 2019. Hence, the "Gov + C&S majority", calculated as the sum of voting Conservative and Democratic Unionist Party members, less the sum of all other voting members, was negative at dissolution.

The following table is a list of MPs elected, ordered by constituency. Names of incumbents are listed where they stood for re-election; for details of other defeated candidates and the incumbent who stood down in those cases see individual constituency articles.