The proposed changes included having a total of 600 seats rather than 650, as agreed by Parliament in 2011 to meet a reformist aim of the 2010–2015 coalition agreement.
The 2013 periodic review of Westminster constituencies began in 2011 and was intended to be completed by 2013, but a January 2013 vote in the House of Commons stopped the process.
The 2018 Review was formally abandoned with the passing of the Parliamentary Constituencies Act 2020, which received Royal Assent on 14 December 2020.
The four boundary commissions submitted their final recommendations to the secretary of state on 5 September 2018,[4][5] and made their reports public a week later.
[10] The proposals were not put forward for approval prior to the calling of the general election held on 12 December 2019, which was contested using the constituency boundaries in place since 2010, as constituted by the fifth periodic review.
Part II of the Act (henceforth referred to as 'PVSaCA') deals with the amendments to the manner in which House of Commons constituencies are formed by the individual boundary commissions.
Following a debate in the House of Lords on 14 January 2013, the Opposition tabled and voted for an amendment to legislation to postpone the date by which the Review ends, which they passed and sent back to the Commons, on a relatively small 69-vote majority.
[21][22] In July 2015, then Prime Minister David Cameron reiterated his plan to go ahead with reducing the number of Members of Parliament and "cut the cost of politics",[23] saying the proposals were "the right approach".
[29] In February 2018, Prime Minister Theresa May was urged by the Public Administration and Constitutional Affairs Committee to deal with the boundary review process as a matter of priority.
[31]At a meeting held in February 2016, the Boundary Commission for Wales confirmed it would recommend 29 constituencies in September of that year.
The Scottish Commission expected few, if any, existing constituencies to remain unchanged and new seats "probably not" all to be constructed from complete electoral wards.
[46] The proposals would also split the town of Dungiven between three constituencies, a change which Órfhlaith Begley (MP for West Tyrone) has described as an "absurdity".
[53] The Parliamentary Constituencies (Amendment) Bill 2017–19, most recently debated in 2017, aimed to replace the Sixth Periodic Review with an entirely new process in time for the next general election.
In June 2020 the High Court of Justice in Northern Ireland ruled on appeal against the Boundary Commission for Northern Ireland for their decision-making during the sixth periodic review of Westminster constituencies, stating in part: It is our view that the barriers unnecessarily erected by the Commission after the [Revised Proposals Report] to representations from members of the public as part of the statutory scheme of consultation subverted the process and unlawfully impugned the [Final Recommendations Report] and its final recommendations.