All Senedd constituencies will have Welsh-language only names from next year, under final decisions by the Democracy and Boundary Commission.

The move has been welcomed by Welsh language campaigners but criticised by ex-Conservative Senedd group leader Andrew RT Davies.

The Cardiff constituencies will also change, under wider reforms, as the number of politicians increases from 60 to 96 at the 2026 Welsh parliamentary election.

Six members will be elected to represent each of 16 new constituencies.

The voting system is changing to become fully proportional.

The commission published its last set of proposals in December.

On that occasion four of the 16 proposed constituencies had bilingual names: Swansea West Gower, South Powys Tawe Neath, Cardiff South-east Penarth and Cardiff North-west.

These will now be called only by their Welsh name: Gŵyr Abertawe, Brycheiniog Tawe Nedd, Caerdydd Penarth and Caerdydd Ffynnon Taf.

The 16 constituencies being fought at the next election will be formed by pairing the 32 constituencies used at the 2024 UK parliamentary election.

Under the commission’s initial proposals, published in September, Cardiff North was paired with Cardiff East and Cardiff West was paired with Cardiff South and Penarth.

However, in December the plans were changed to pair Cardiff North with Cardiff West and Cardiff East with Cardiff South and Penarth.

The commission has now decided to revert to the original plans, forming two new constituencies called Caerdydd Ffynnon Taf and Caerdydd Penarth.

Under the law for the new Senedd each constituency had to be given a single name “unless the commission considers this would be unacceptable”.

Having now assigned all 16 constituencies Welsh-only names, the commission says it believes the titles chosen are “acceptable and recognisable for people across Wales”.

On Sunday, commission chief executive Shereen Williams told the BBC Sunday Supplement programme that previous proposals to give most seats Welsh-only names had prompted “pushback” during a recent consultation.

Many of the comments received reflected “anti-Welsh language sentiments”, she said, which she found “incredibly disappointing”.

Announcing its final decisions on Tuesday, Williams said: “The debate over proposed pairs and names has been robust, but very constructive, and the constituencies recommended by the commission have been significantly strengthened due to the public’s involvement in the process.”

A further review of the constituencies will take place ahead of the 2030 Senedd election.

The former leader of the Conservatives in the Senedd has expressed his opposition to the Welsh-only names.

Andrew RT Davies said on X (formally known as Twitter): “Many constituents wrote to the boundary commission, complaining that the proposed Welsh-language only constituency names disenfranchised them.

“They were ignored.

“Wales is bilingual and constituency names should be in both languages.”

But Joseff Gnagbo, national chair of Welsh language campaign group Cymdeithas yr Iaith, welcomed the naming policy as setting “an important precedent for the names of constituencies in the future and for using Welsh-only names in other contexts as well”.