Statutory instruments in the context of "Constituencies of the Parliament of the United Kingdom"

The Parliament of the United Kingdom currently has 650 parliamentary constituencies across the constituent countries (England, Scotland, Wales, and Northern Ireland), each electing a single member of parliament (MP) to the House of Commons by the plurality (first-past-the-post) voting system, ordinarily every five years. Voting last took place in all 650 of those constituencies at the United Kingdom general election on 4 July 2024.

The number of seats rose from 646 to 650 at the 2010 general election after proposals made by the boundary commissions for England, Wales, and Northern Ireland (the Fifth Periodic Review of Westminster constituencies) were adopted through statutory instruments. Constituencies in Scotland remained unchanged, as the Boundary Commission for Scotland had completed a review just before the 2005 general election, which had resulted in a reduction of 13 seats.