The current review is the seventh general review of UK Parliamentary constituency boundaries. These are conducted by independent and impartial boundary commissions, 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 Wales will be reduced from 40 to 29.
The Boundary Commission for Wales must report its final recommendations to the Government by 1 October 2018. The new boundaries will take effect at the 2020 General Election.
The initial proposals of the Boundary Commission for Wales were published on 13 September 2016 in English and Welsh.
The Boundary Commission for Wales has proposed that Cardiff has three constituencies, one fewer than now.
Newport is reduced to a single seat which comprises all but five wards of the County and City of Newport council area.
Swansea retains two seats but both have proposed seats take in a wider area surrounding the existing seats.
Sixteen existing seats are wholly contained within a proposed new constituency. Where a new name is proposed to reflect the geographical alteration this is included in the bracket:
- Alyn and Deeside
- Blaenau Gwent
- Brecon and Radnorshire (Brecon, Radnor and Montgomery)
- Bridgend (Bridgend and Vale of Glamorgan West)
- Cardiff West
- Ceredigion (Ceredigion a Gogledd Sir Benfro)
- Cynon Valley (Cynon Valley and Pontypridd)
- Llanelli (Llanelli and Lliw)
- Merthyr Tydfil and Rhymney
- Neath (Neath and Aberavon)
- Ogmore (Ogmore and Port Talbot)
- Rhondda (Rhondda and Llantrisant)
- Swansea East
- Wrexham (Wrexham Maelor)
- Ynys Môn (Ynys Môn ac Arfon)
Three constituency names have been retained with modifications to the boundaries other than a complete transfer of an existing seat:
- Cardiff North
A number of seats will be abolished under these proposals.
- Dwyr Meirionnydd
- Clwyd West
- Vale of Clwyd
- Preseli Pembrokeshire
- Carmarthen West and Pembrokeshire South
- Carmarthe East and Dineffwr
- Vale of Glamorgan
- Newport East
- Newport West
- Cardiff Central
- Cardiff South and Penarth
These, in part, make way for new seats proposed by the Commission:
- Colwyn and Conwy
- Flint and Rhuddlan
- Gogledd Clwyd a Gwynedd
- De Clwyd a Gogledd Sir Faldwyn
- South Pembrokeshire
- Gower and Swansea West
- Vale of Glamorgan East
- Cardiff South and East
Publication of the initial proposals started the initial public consultation process.
Anyone could submit written representations to the Commission and the Commission welcomed submissions in either English or Welsh. Submissions could be submitted either online, via email or by post. Oral representations were also possible at one of the four public hearings.
The Commission will publish all the representations received during the initial consultation on 28 February 2017. At the same time it will publish transcripts of the public hearings. This will trigger the secondary phase of the consultation, which will last for four weeks
There is more information on the public participation process in the Library briefing CBP-7696 Parliamentary boundary reviews: public consultations
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 2020 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.