Casnewydd Islwyn
Senedd constituency covering Newport and Islwyn.
Casnewydd Islwyn is represented by Dan Thomas, WHO quit as Reform UK's leader in Wales on 15 September 2026 after Gwent Police arrested him; he remains one of the constituency's six Members of the Senedd.
Last refreshed: 7 October 2026 · Appears in 1 active topic
Who represents Newport and Islwyn in the Senedd?
Timeline for Casnewydd Islwyn
Mentioned in: Rhun ap Iorwerth sets six goals for Wales
UK Local Elections 2026Background
Casnewydd Islwyn is one of 16 six-member constituencies that elect the 96-seat Senedd. The Senedd Cymru (Members and Elections) Act 2024 created it, and its first election was held on 7 May 2026. It joins Newport with Islwyn, matching the Westminster seats of Newport East and Newport West and Islwyn, and returns its members by Closed-list proportional representation.
At that first contest Reform UK led with 32.9% of the vote to Plaid Cymru's 29.7%. Each of those parties took two seats, and Labour and the Conservatives one each. The members are Dan Thomas and Art Wright for Reform UK, Peredur Owen Griffiths and Lyn Ackerman for Plaid Cymru, Jayne Bryant for Labour and Natasha Asghar for the Conservatives.
Thomas's arrest and resignation in September 2026 put the constituency at the centre of Reform's leadership change.
Its Reform member quits the leadership
Thomas, one of two Reform UK members returned for Casnewydd Islwyn in May 2026, stood down as the party's Welsh leader on 15 September 2026 after his arrest by Gwent Police. He was bailed and has not been charged, insists he has done nothing wrong, and continues to sit for the constituency.
For the seat's voters the change is one of party rank, not of representation: all six members elected in May remain in place. Reform's group chose Helen Jenner, WHO sits for Bangor Conwy Môn, as Thomas's successor on 21 September, so the party's Welsh leadership has moved from the south-east of Wales to the north-west.
Which areas are in the Casnewydd Islwyn Senedd constituency?
Who are the MSs for Casnewydd Islwyn?
How many members does Casnewydd Islwyn elect?
