Proposals for new parliamentary constituency boundaries in England, Scotland and Northern Ireland will be published this week by the relevant Boundary Commissions. The Commission in Wales published its revised proposals in October.

This Insight explains what boundary reviews are, progress of the current review, and what comes next.

What is a boundary review?

Each MP represents a single parliamentary constituency and the boundaries of these are reviewed periodically. This is to account for population changes and realign constituency boundaries with other administrative boundaries that may have changed in intervening years.

The current boundaries were implemented at the 2010 General Election in England, Wales and Northern Ireland and at the 2005 General Election in Scotland.

Reviews are carried out by four Boundary Commissions, one for each nation of the UK. They are independent and impartial but must follow the Rules of Redistribution set out in legislation and agreed by Parliament.

The Rules say there must be 650 seats in the House of Commons, and these are allocated to each country based on the number of registered electors in each country.

The Rules also say all constituencies must have a similar sized electorate, except for five island seats: Orkney and Shetland, Na hEileanan an Iar, Ynys Môn, and the two seats allocated to the Isle of Wight.

There are several stages of public consultation that must be held before final recommendations are produced.

The current review

The 2023 Review was formally launched on 5 January 2021 and must be completed by 1 July 2023.

The current allocation of seats for each country is shown in the table below.

2023 Review – allocation of seats

Source: Boundary Commission
Note: The parliamentary electorates as of 1 March 2020 and can be viewed in the ONS release Electoral statistics, UK: March 2020
Country Electorate Current 2023 Review Change
 England 39,860,421 533 543 10
 Scotland 4,079,612 59 57 -2
 Wales 2,332,677 40 32 -8
 Northern Ireland 1,295,688 18 18 0
 Total 47,558,398 650 650

The Commissions must create constituencies with no fewer than 69,724 and no more than 77,062 voters (other than for the island seats).

Each Commission produced initial proposals in 2021. Two stages of public consultation were held on those initial recommendations over 2021 and 2022, which included public hearings.

The Library briefing, Parliamentary boundary reviews: public consultations, has more information on the consultation.

Revised proposals

The Commissions have revised their proposals based on representations during the first two stages of consultation.

This triggers a third round of consultation lasting four weeks. Written submissions are encouraged by the Commissions but there are no more public hearings.

Details of revised proposals are set out on each Commission’s website:

What happens next?

The Commissions will consider representations received in all stages of the consultations. They will then decide whether to make further adjustments before announcing final recommendations.

Final recommendations

The Commissions are required to report their final recommendations to the Speaker of the House of Commons by 1 July 2023.

Once the Speaker receives a final report, it must be laid before Parliament. The Commissions must publish their report once they have been laid.

There is no formal parliamentary stage or vote on the final recommendations and Parliament is unable to amend them.

At the same time as submitting a report to the Speaker, each Commission must send a copy of its final report to the Government.

Once the final reports are submitted the four Commissions have completed their role in the review.

Implementing the Boundary Review changes

After the Government receives all four sets of final recommendations it is responsible for drawing up a single draft Order in Council to implement the recommendations. Orders in Council are Orders that have been approved at a meeting of the Privy Council personally by The King.

The Government must submit the draft Order to the King in Council for approval “as soon as reasonably practicable”. The legislation states this must be no later than four months after the final reports have been laid in Parliament unless there are exceptional circumstances.

The draft Order must contain the final recommendations of the Boundary Commissions. The Government cannot make changes.

When will the boundaries be used?

The new boundaries will be used at the first general election after the Order comes into force. The date it comes into force will be included in the Order itself.

The validity of an Order in Council, once made, cannot be called into question in any legal proceedings.

If there are by-elections held between the Order being made and the next general election, the current boundaries are used.

Further reading

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

Photo by Benjamin Elliott on Unsplash

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