House of Commons Library

UK parliamentary by-elections since 1945

Published Wednesday, July 4, 2018

The number of UK by-elections by session and by Parliament since 1945

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This list notes the number of by-elections by session since 1945-46 and also gives the results for by-elections since 2005.

Chart showing the number of by-elections since 1945

A larger version of this chart can be found in the spreadsheet.

When do by-elections happen?

A by-election occurs when a seat in the House of Commons becomes vacant during the lifetime of a Parliament (ie between general elections), because the sitting MP dies, resigns, is elevated to the peerage, or becomes ineligible to sit for some other reason. There have been two by-elections in the current 2017 Parliament.

Further information

The by-elections page of the Parliament website provides detailed information on results, including the number of votes cast and percentage share.

See the Commons briefing on UK Election Statistics: 1918-2010 for a list of all by-elections in Great Britain and Northern Ireland.


Please send any comments or corrections to: Parliamentary Information Lists Editor, Parliament and Constitution Centre, House of Commons, SW1A 0AA. Suggestions for new lists welcomed.


Commons Briefing papers SN02383

Author: Sarah Priddy

Topics: By-elections, Elections

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