Parliamentary constituencies
Under the 1986 Act, there are four Boundary Commissions in the United Kingdom: one each for England, Wales, Scotland and Northern Ireland who are required (currently every 5 years) to carry out a review of the parliamentary constituencies in their part of the UK, and to submit to Government a report of their recommendations on the constituencies into which their part of the UK should be divided.
	The Parliamentary Voting System and Constituencies Act 2011 ("the PVSC Act 2011") amended the 1986 Act to provide for more equal-sized constituencies and also to reduce the number of constituencies, and therefore MPs, in the UK from 650 to 600. Under these changes, at future boundary reviews, the electorate of all constituencies, subject to a limited number of exceptions, should be no less than 95% and no more than 105% of the UK electoral quota (that is the average number of electors in a constituency). Under these provisions, there are four protected constituencies: the two constituencies on the Isle of Wight, the single constituency of Orkney and Shetland and the constituency of Na h-Eileanan an Iar (formerly the Western Isles). As protected constituencies, they are permitted to deviate from the rule that no constituency electorate size should vary more than 5% from the UK electoral quota.
	The PVSC Act 2011 also made amendments to the process of public consultation in boundary reviews, which included providing for three separate consultation stages (amounting to 24 weeks in total) and the introduction of public hearings at which individuals could make representations in person on the Boundary Commissions’ proposals.
	The PVSC Act 2011 required the Boundary Commissions to carry out a first boundary review of the constituencies within their part of the UK under the new provisions and to submit their final reports by 1 October 2013; thereafter boundary reviews would be held every 5 years. The Electoral Registration and Administration Act 2013 subsequently postponed the deadline for the submission of reports of that first review until 2018. The Boundary Commissions were required to carry out a fresh review and submit their final reports in September 2018.
	The four Boundary Commissions commenced the 2018 boundary review in February 2016 in accordance with the changes made by the PVSC Act 2011 and submitted their final reports to the Government on 5 September 2018. The Government laid the reports before Parliament and arranged for them to be published on 10 September 2018. The recommendations of the 2018 boundary review have not been implemented.