Wales: New Constituency Boundaries 2023

Each new seat can be described as a combination of parts of old seats. These tables show this decomposition. The winner of the old seat at the 2019 election is shown by party colour, as is the implied winner of the new seat.

The implied results are calculated using the local election results for the wards which make up each old seat. This should give the most accurate projection, since it reflects varying political behaviour across the seat.

Wales Change Table

PartyOld SeatsNew SeatsChangeDisappearSwitch OutSwitch InFresh

The table shows how the various changes affect each party in this area. The total old and new seats are shown for each party, as well as their difference ('Change'). The change in seats is also explained through the four explanations:

The old seats which are disappearing are: Arfon; Carmarthen West and Pembrokeshire South; Clwyd South; Cynon Valley; Newport West; Ogmore; Swansea East; Vale of Clwyd.

The old seats which are lost to another party are: Carmarthen East and Dinefwr.

The new seats which are gained from another party are: Carmarthen.


New seatPrimary componentSecondary component(s)
Alyn and Deeside 100% of Alyn and Deeside 23.1% of Delyn
Bangor Aberconwy 100% of Aberconwy 40.9% of Arfon
14.2% of Clwyd West
Clwyd East 76.9% of Delyn 35.9% of Vale of Clwyd
16.1% of Clwyd West
9.1% of Clwyd South
Clwyd North 69.8% of Clwyd West 64.1% of Vale of Clwyd
Wrexham 100% of Wrexham 39.2% of Clwyd South


New seatPrimary componentSecondary component(s)
Carmarthen 84.2% of Carmarthen East and Dinefwr 40.7% of Carmarthen West and Pembrokeshire South
Ceredigion Preseli 100% of Ceredigion 30.1% of Preseli Pembrokeshire
Llanelli 100% of Llanelli 15.8% of Carmarthen East and Dinefwr
Pembrokeshire Mid and South 69.9% of Preseli Pembrokeshire 59.3% of Carmarthen West and Pembrokeshire South


New seatPrimary componentSecondary component(s)
Blaenau Gwent and Rhymney 100% of Blaenau Gwent 20.3% of Merthyr Tydfil and Rhymney
9.2% of Caerphilly
4.8% of Islwyn
Caerphilly 90.8% of Caerphilly 24.6% of Islwyn
Monmouthshire 88.2% of Monmouth 23.0% of Newport East
Newport East 77.0% of Newport East 45.8% of Newport West
Newport West and Islwyn 70.6% of Islwyn 54.2% of Newport West
Torfaen 100% of Torfaen 11.8% of Monmouth


New seatPrimary componentSecondary component(s)
Dwyfor Meirionnydd 100% of Dwyfor Meirionnydd 59.1% of Arfon
5.1% of Clwyd South
Ynys Mon (Anglesey) 100% of Ynys Mon

Mid Glamorgan

New seatPrimary componentSecondary component(s)
Bridgend 82.8% of Bridgend 31.8% of Ogmore
Merthyr Tydfil and Aberdare 79.7% of Merthyr Tydfil and Rhymney 58.1% of Cynon Valley
0.0% of Brecon and Radnorshire
Pontypridd 70.9% of Pontypridd 41.9% of Cynon Valley
16.4% of Ogmore
Rhondda and Ogmore 100% of Rhondda 24.2% of Ogmore
15.4% of Pontypridd


New seatPrimary componentSecondary component(s)
Brecon, Radnor and Cwm Tawe 100% of Brecon and Radnorshire 30.4% of Neath
Montgomeryshire and Glyndwr 100% of Montgomeryshire 46.6% of Clwyd South

South Glamorgan

New seatPrimary componentSecondary component(s)
Cardiff East 78.2% of Cardiff Central 32.4% of Cardiff South and Penarth
Cardiff North 100% of Cardiff North 4.7% of Pontypridd
0.1% of Cardiff South and Penarth
Cardiff South and Penarth 67.5% of Cardiff South and Penarth 21.8% of Cardiff Central
8.3% of Vale of Glamorgan
Cardiff West 100% of Cardiff West 8.9% of Pontypridd
1.2% of Ogmore
Vale of Glamorgan 91.7% of Vale of Glamorgan

West Glamorgan

New seatPrimary componentSecondary component(s)
Aberafan Maesteg 83.8% of Aberavon 26.4% of Ogmore
17.2% of Bridgend
1.6% of Neath
Gower 90.8% of Gower 33.9% of Swansea West
1.0% of Swansea East
Neath and Swansea East 68.0% of Neath 37.4% of Swansea East
16.2% of Aberavon
9.2% of Gower
Swansea West 66.1% of Swansea West 61.6% of Swansea East