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The current review is the seventh general review of UK Parliamentary constituency boundaries. These are conducted by independent and impartial boundary commission, one for each country of the UK.

Parliamentary constituency boundaries are periodically reviewed to take account of changes in electorates but the boundary commissions also take the opportunity to realign constituency boundaries so they coincide with other administrative boundaries, such as local government boundaries.

The 2018 Review will reduce the number of seats in the House of Commons from 650 to 600. The number of seats in Northern Ireland will be reduced from 18 to 17.

The Boundary Commission for Northern Ireland published its initial proposals on 6 September 2016 and the initial consultation closed on 28 November 2016. The secondary consultation period of four weeks will start on 5 September 2017.

Since the last review of constituency boundaries the structure of local government in Northern Ireland has been reformed. As a result of changes in ward boundaries it is not possible to track electorate changes from current constituencies to the Commission’s proposed constituencies.

Initial proposals

The proposed constituency with the largest electorate is Strangford (74,741). The proposed seat with the smallest electorate is Belfast North West (71,266).

The proposed constituency covering the largest geographical area is Fermanagh and South Tyrone (3,083 km2). The proposed constituency covering the smallest area is Belfast East (45 km2).


In its initial proposals the Commission has recommended that Belfast should have three rather than four seats. The three seats will be almost wholly contained within the boundary of the new Belfast local government district.

The Belfast local government district has a theoretical entitlement to 2.87 seats. With the addition of just two wards from other districts the Commission has proposed three new constituencies. The current four seat arrangement includes a number of wards from local government districts surrounding Belfast.

Outside Belfast

Beyond Belfast there are modifications to eight seats:

  • North Down,
  • Strangford,
  • South Down,
  • Newry and Armagh,
  • Fermanagh and South Tyrone,
  • Foyle,
  • East Antrim,
  • South Antrim.

 The Commission proposals abolish five seats:

  • Lagan Valley,
  • Mid Ulster,
  • West Tyrone,
  • East Londonderry,
  • North Antrim

Proposed new seats are called:

  • Dalriada
  • Glenshane
  • North Tyrone
  • Upper Bann and Blackwater
  • West Antrim
  • West Down

Public consultation

The publication of the initial proposals triggered the first stage of the public consultation process. This first stage, which closed on 28 November 2016, included public hearings as well as allowing for written submissions to the Commission.

The Commission will publish all the representations received during the initial consultation. At the same time it will publish transcripts of the public hearings held in October 2016. This triggers the secondary consultation period of four weeks.

The Commission has announced that the secondary consultation will start on 5 September 2017.

If the Commission decides to revise its proposals in the light of representations received it will publish a new report. This is likely to be in the autumn of 2017.

There is more information on the public participation process in Library briefing CBP-7696, Parliamentary boundary reviews: public consultations

The four commissions are required to publish their final recommendations and reports before 1 October 2018.

Once the reports and recommendations are submitted to the Government the four commissions’ involvement in the review is concluded.

Parliamentary approval

Once the Government receives the reports from the four boundary commissions it must lay them before Parliament. If any new constituency boundaries are required, the Government must lay a draft Order in Council before Parliament to give effect to the changes.

The draft Order in Council must be approved by both Houses of Parliament. If approved the Orders are submitted to be made by Her Majesty in Council.

The constituencies do not take effect until the next general election, due to be May 2022 under the provisions of the Fixed-term Parliaments Act 2011.

Any by-elections in the time between the Orders being approved and the next general election are held using the current constituency boundaries.

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