On 5 September 2018, all four Boundary Commissions submitted their final reports and recommendations for new Parliamentary constituency boundaries to the Government. On 10th September, the Government laid the Commissions’ reports and made them available online.

But what can we expect to happen next? This Insight (updated on 10 September to reflect the publication of the reports) recaps what boundary reviews are and outlines the steps after the submission of the 2018 Review.

What is the boundary review?

Parliamentary constituency boundaries 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 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 set out in legislation passed by Parliament in 1986 and amended in 2011. The legislation also sets out the stages of public consultation that must be held during reviews and when the reports must be submitted to the Government.

Existing boundaries

Current constituency boundaries are a result of the most recent completed review, the Fifth Periodical Review. They were implemented at the 2010 General Election in England, Wales and Northern Ireland and at the 2005 General Election in Scotland.

New rules: equalising electorates

The Sixth Review, known as the 2013 Review, was to be the first to use the new Rules of Redistribution and would have reduced the number of seats in the House of Commons from 650 to 600. The new Rules also placed primary importance on equalising electorates between constituencies.

The 2013 Review was abandoned before being completed, due to disagreement within the Coalition Government. There is background to the events leading to the ending of the 2013 review and on how reviews work in the Library briefings, Constituency boundary reviews and the number of MPs and Parliamentary boundary reviews: public consultations.

The current review

The 2018 Review is the seventh general review of constituency boundaries and was launched on 24 February 2016.

Once the four Boundary Commissions have submitted their final recommendations and reports to the Government in September 2018, their roles will end.

Laying the reports

Once the Government receives the reports from the four Boundary Commissions, it must lay them before Parliament. The legislation states the Government must do this “as soon as may be”. The exact timing is up to the Government.

The Government laid the reports of all four Commissions on Monday 10 September and made them available on the gov.uk website. At the same time the commissions published details on their websites.

Before the 2013 Review (when the Rules of Redistribution changed) the four Commissions reported at differing times. The time between the reports being handed to the Government and laid before Parliament also varied.

For the Fifth Review, the time periods were as follows.


Report handed to Government

Report laid in Parliament
Scotland 30/11/2004 14/12/2004
Wales 31/01/2005 14/12/2005
England 31/10/2006 26/02/2007
Northern Ireland 14/09/2007 31/03/2008

The Labour Government deferred laying the report of the Boundary Commission for Wales for almost 12 months, due to the imminent 2005 General Election. The 2001-05 Parliament could have gone on until May 2006 but commentators had widely expected the poll to be held in May 2005.

Laying the draft Order

Once the reports have been laid in Parliament, the Government is responsible for laying a single draft Order in Council, to give effect to the Commissions’ recommendations. This also has to be done “as soon as may be”. In the most recent completed reviews the reports and the draft Orders have been laid at the same time.

Chloe Smith, speaking at the 12th committee stage session of the Parliamentary Constituencies (Amendment) Bill 2017-19 on 5 September, said that the draft Order “will take some months to prepare”.

Once laid, the draft Order must then be approved by both Houses of Parliament. At this stage the Government can’t alter the recommendations unless it has been requested to, in writing, by one of the four Boundary Commissions. A Commission would only do so if it became aware of a factual error in its data.

If the draft Order is not approved, the Government may then lay an amended draft Order before Parliament for approval. This again would need to be approved by both Houses of Parliament. No Government has amended a draft Order.

In the Commons, the draft Orders are usually considered by a Delegated Legislation Committee before formally being approved by the whole House. Previous reviews had a separate draft Order for each part of the UK.  The dates for each stage after the draft Orders implementing the Fifth Review were laid are shown below.

  Delegated Legislation Committee Approved House of Commons Approved House of Lords Order made by Her Majesty
Scotland 24/01/2005 25/01/2005 01/02/2005 09/02/2005
Wales 16/02/2006 28/02/2006 09/03/2006 11/04/2006
England 27/03/2007 16/04/2007 17/05/2007 13/06/2007
Northern Ireland 15/05/2008 02/06/2008 22/05/2008* 11/06/2008

*Lords Grand Committee considered the draft Order on 20/05/2008

Order in Council

Once the draft Order in Council has been approved by Parliament, the Government is required to submit it to be made by Her Majesty in Council.

Orders in Council are Orders that have been approved at a meeting of the Privy Council personally by The Queen. The Order will include a date on which the Order will come into force.

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

And when will the boundaries be used?

The constituencies do not take effect until the next general election after the Order comes into force.

If an early election is called, the constituency boundaries to be used will depend on whether the Order in Council has been made and come into force.

Any by-elections in the time between the Order being made and the next general election are held using the current (Fifth Review) constituency boundaries.

Neil Johnston is an election specialist at the House of Commons Library.