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MPs' changes of party allegiance in the House of Commons since 1979

Is there a by-election if an MP changes Party?

No. By-elections are not automatically triggered if an MP changes their party affiliation although an MP may choose to stand down and fight the ensuing by-election under a new party label or as an independent MP.

Role of the Whips Office

Information on the role of the government and opposition whips in the management of parliamentary business can be found in the Commons Library briefing on the Whips’ Office.

Parliament: facts and figures

• Browse all briefings in the series

This series of publications contains data on various subjects relating to Parliament and government. Topics include legislation, MPs, select committees, debates, divisions and Parliamentary procedure.

Feedback

Due to the difficulties in compiling a comprehensive list of all floor-crossings, whip withdrawals and whip resignations, this list cannot be guaranteed to be definitive.

We are always happy to hear of any additions or amendments to the list. Please email papers@parliament.uk with any comments.