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This briefing summarises the consultation process during the reviews of Parliamentary constituency boundaries.

Periodic reviews

Parliamentary constituency boundaries reviews are undertaken by independent Boundary Commissions. The number of constituencies in the UK is fixed at 650. Periodic reviews occur so that constituencies are altered occasionally to take account of changes in population over time. Changes are also made to reflect local government boundary changes, so that administrative boundaries coincide as much as possible.

There is more information on the background to boundary reviews and the number of Members of Parliament in the Library briefing Constituency boundary reviews and the number of MPs.

The next review must be completed by 1 July 2023. Subsequent reviews will be required every eight years. The four Commissions, one for each of the nations of the UK, announced they were starting the 2023 Review on 5 January 2021.

The Commissions will publish more details on their websites:

Boundary Commission for England

Boundary Commission for Scotland

Boundary Commission for Wales

Boundary Commission for Northern Ireland

Public consultations

As part of the of the boundary review process each Boundary Commission is required to hold public consultations on their proposals. The statutory provisions that the Commissions must follow are set out in the Parliamentary Constituencies Act 1986, as amended.

When a Commission publishes initial or revised recommendations for proposed constituency boundaries the publication triggers the public consultation provisions. The timing of the publication of recommendations remains a decision for the Commissions.

For the 2023 Review the following consultation periods will be held:

  • The initial consultation period – initial proposals will be published triggering an 8-week consultation where written submissions may be made. Each Commission must publish all submissions received at the end of the 8-week period.
  • The secondary consultation period – publication of the initial submissions triggers a second 6-week period, including public hearings. The public can make additional representations, including counter-proposals to those responses received in the first eight-week period.
  • The third consultation period – if, after the initial and secondary periods, a Commission decides to revise its proposals then publication of revised recommendations will trigger a third consultation lasting 4 weeks. No public hearings will be held.

Timings for subsequent reviews will be altered so each of the three phases of consultation must last 8 weeks. Section 2 gives more detail.

The new public consultation format was introduced in 2011. These provisions were used in the 2013 and 2018 Reviews. The Parliamentary Constituencies Act 2020 altered the consultation phases by moving the public hearing stage of the consultation from the initial phase to the secondary phase. This change was based on the feedback the Government had received from the Commissions to improve the effectiveness of public hearings. Background to the changes is in the Library briefing paper on the Parliamentary Constituencies Bill 2019-21.

By holding public hearings in the secondary phase, rather than the initial phase, the Commissions said they would be able to better target where to hold public hearings. The Commissions would know the areas generating the most concern and hold hearings in those areas. It would also assist those wanting to make oral submissions at the hearings to comment on or provide counter-arguments to submission made in the initial phase.

The 2020 changes also temporarily altered the timings of the consultation for the next review, the 2023 Review. The 2023 Review is to be conducted over a shorter period than subsequent reviews. This is following the Government’s decision to abandon the 2018 Review, which would have reduced the size of the House of Commons to 600 seats and maintain the House at 650 seats. The 2023 Review must be completed by 1 July 2023.


The 2023 Review will be the first to be implemented under the new arrangements brought in by the Parliamentary Constituencies Act 2020. The final reports of the Commissions must be delivered to the Speaker of the House of Commons. At the same time the Commissions must send copies to the Government.

The Government must draw up a draft Order in Council containing the final recommendations of the Commissions without amendment. Parliament has no role in approving the draft Order. It is submitted to Her Majesty in Council, where it is approved.

Once the draft Order is approved the boundaries are implemented at the next general election.

Previously the public consultation process was based on an inquiry system. If enough written submissions on initial proposals published by a Commission were received, an assistant commissioner, who would be a lawyer, would be appointed to conduct a quasi-judicial inquiry. There was no statutory procedure for local inquiries and the operation of them was left to the discretion of the assistant commissioner. Section 3.1 briefly explains the old inquiry process.

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