Today the Boundary Commission for England published its first set of proposals for new constituency boundaries. The Boundary Commissions for Northern Ireland, Scotland and Wales will publish theirs later in the year. This is the third time in 10 years that the Commissions have started a review of UK Parliament constituencies.

Public consultation is an important part of the reviews. At each stage the public get an opportunity to give feedback on recommendations.

This Insight explains what happened to the two previous reviews and how to contribute to this one.

What are boundary reviews?

UK Parliamentary constituency boundaries are reviewed periodically to take account of population changes. There are currently 650 constituencies. The existing boundaries in England, Wales and Northern Ireland were implemented in 2010. In Scotland, it was 2005.

Reviews are carried out by four Boundary Commissions, one for each part of the UK. They are independent and impartial but must follow the Rules of Redistribution.

New Rules in 2011

In 2011, Parliament approved new Rules of Redistribution that fixed the number of seats in the House of Commons at 600. The number for each part of the UK was calculated using the total electorate. The Rules also set out that reviews should happen every five years.

Another new rule meant all seats had to have an electorate within 5% of the electoral quota. The electoral quota is the average electorate, or number of registered voters, per seat. Four island seats were exempt from this rule – Orkney and Shetland, Na h-Eileanan an Iar, and the two seats for the Isle of Wight.

Older reviews had always included a rule to make constituencies roughly the same size, but the change in 2011 made this the primary rule.

The 2013 and 2018 reviews

Two reviews using the new 2011 rules began, but neither was implemented.

The 2013 Review was abandoned in January 2013 before final recommendations were produced. The 2018 Review was completed by all four Commissions and their reports were handed to the Government but was not implemented.

In March 2020, the Government announced that it no longer favoured the reduction in the number of seats in the House of Commons to 600. Instead it would introduce a new bill to fix the number at 650. One reason given is that following the UK’s exit from the European Union, MPs will have greater workloads.

Changes in the Rules in 2020

In 2020, Parliament agreed the new legislation. This fixed the number of seats at 650 and cancelled the 2018 Review.

Other changes included allowing for reviews every eight years, instead of five, and moving public hearings to later in the consultation process. The most controversial change was to how a review is implemented – it is now automatic (see more below). The debates are summarised in the Library briefing on the bill.

Some changes from 2011 were kept. The seats for the four nations of the UK are still allocated by calculating the proportion of the electorate in each. For example, England has 84% of registered voters so it was allocated 84% (543) of the seats for the 2023 Review.

The 5% rule remains the primary rule, however, a new seat was added to the list of exempt island seats – Ynys Môn, on the north-west coast of Wales.

The 2023 Review

The Boundary Commissions announced the start of the new review in January 2021. Each Commission can choose when to publish proposals and consult, but they must hand over a final report by 1 July 2023.

There are likely to be big changes even though the overall number of seats is staying at 650. This is because there will have been a lot of population movement in the time since the last set of boundaries were formulated.


The Commissions say they value responses but advise that if someone disagrees, their response might be more useful if it proposes workable alternatives. See, for example, the Boundary Commission for England’s guide to the 2023 Review.

All responses must be treated equally, regardless of how they are received. They may be electronic, in hard copy or in person at a public hearing.

This is how the public consultation will work for the 2023 Review:

The initial consultation period

Publishing initial proposals triggers an eight-week consultation. This stage allows written representations.

Each Commission must publish all submissions received at the end of the eight weeks. Publishing these triggers the secondary consultation.

The secondary consultation period

This lasts six weeks. Representations can include comments on submissions from the initial consultation.

The secondary period includes public hearings, which each region must hold. There must be at least two and no more than five per region, lasting up to two days.

After the secondary consultation period, each Commission must publish any written submissions and transcripts of the public hearings.

The third consultation period

If a Commission decides to publish revised proposals because of the first two consultation periods, this triggers a third consultation.

This lasts four weeks and there are no public hearings.

Final recommendations

The reports are handed to the Speaker of the House of Commons and are formally laid before Parliament (this time, by 1 July 2023).

Parliament has no say in accepting or rejecting the final recommendations. They are automatically implemented after being laid.

The Government also receives copies and must present a single draft Order in Council to implement the recommendations. Orders in Council are approved at a meeting of the Privy Council personally by the Queen.

Once approved, the new boundaries take effect at the next general election.

Further reading

Constituency boundary reviews and the number of MPs, House of Commons Library.

Parliamentary boundary reviews: public consultations, House of Commons Library.

Details of the 2023 review and how to get involved in the public consultations can be found on the Commissions’ websites:

About the author: Neil Johnston is a researcher at the House of Commons Library, specialising in elections.

Photo by Jay Mullings on Unsplash

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