Senedd boundaries face fresh review ahead of 2030 election

Senedd constituency boundaries across Wales could face further changes as part of a new review.

The Democracy and Boundary Commission Cymru has launched its guidance for the 2030 Review, outlining how Wales’ 16 Senedd constituencies will be redrawn.

The previous review paired 32 Westminster parliamentary seats to create 16 multi-member Senedd constituencies, which were used for the first time at the Senedd election in May.

The changes saw the Caerphilly seat merged with the Blaenau Gwent and Rhymney seat, to create Blaenau Gwent Caerffili Rhymni – while Newport West and Islwyn was merged with Newport East to form Casnewydd Islwyn.

However, legislation passed in 2013 requires officials to conduct a fresh review using more flexible criteria.

Instead of relying on paired parliamentary seats, commissioners will use a strict electoral quota.

Every constituency must fall within 10% of the average number of electors across Wales, which currently sets the target range between 135,225 and 165,275 voters per seat.

Commissioners will also evaluate local government boundaries, physical geography, and established community ties, while attempting to minimise disruption to voters. Political outcomes, postcode allocations, and service boundaries will not be considered.

The commission is also tasked with naming each seat, with rules stating constituencies should feature a single-language name unless deemed unacceptable. The names of all 16 Senedd constituencies currently in use are in Welsh only.

Shereen Williams MBE OStJ is the commission’s chief executive. She said: “Whenever the commission holds a review, the public’s feedback, especially on their local area, is vital to making sure our determinations are the strongest possible.

“The move from pairing parliamentary constituencies to using an electoral quota does mean that some changes will be necessary at this review, but it also gives us an opportunity to respond with greater flexibility to the public’s views, while ensuring that we minimise changes wherever we can.”

Initial proposals will be published in early 2027, launching an eight-week public consultation. A second consultation stage will feature public hearings, followed by a four-week review of any revised plans.

Final determinations must be submitted to Welsh Government ministers before December 1, 2028, coming into effect for the 2030 Senedd election.