Dan Thomas has resigned as the leader of Reform UK in Wales following his arrest on suspicion of assault and coercive behaviour.
The Member of the Senedd (MS) for Casnewydd Islwyn resigned as leader of Reform UK in Wales on Tuesday, 15 September 2026, two days after he was detained by Gwent Police. The party has appointed Helen Jenner as interim leader while it prepares to select a permanent replacement by the end of the month.
Gwent Police confirmed that a 45-year-old man from the Aberbargoed area was arrested on Sunday, 13 September. A spokesperson for the force stated the arrest was on suspicion of assault and engaging in controlling or coercive behaviour. He has since been released on bail pending further enquiries.
In a statement addressing his resignation, Mr Thomas maintained his innocence, asserting that he has “done nothing wrong”. He said he had chosen to stand aside to prevent media coverage of the investigation from becoming a “distraction” to the party’s work in the Welsh Parliament.
While Mr Thomas has resigned from his leadership role, he continues to serve as the MS for Casnewydd Islwyn.
The resignation comes at a period of significant instability for Reform UK in Wales. On the same day Mr Thomas stepped down, Sarah Cooper-Lesadd, the MS for Pen-y-bont Bro Morgannwg, announced her defection from Reform UK to Plaid Cymru.
The loss of a leader and the defection of a Senedd Member in a single 24-hour period marks a substantial shift in the political landscape in Cardiff Bay.
According to ITV Wales, the party’s remaining MSs are expected to vote on a permanent successor to Mr Thomas by the end of September.
Mr Thomas had previously claimed he was “released without charge” following his arrest; however, Gwent Police records clarify that his legal status remains “bailed pending further enquiries.” Under Welsh Parliament rules, an MS remains in office unless they choose to resign or are disqualified under specific legal criteria, such as a prison sentence of more than a year.