Dan Thomas has stepped down as Reform UK’s Welsh leader after his arrest on suspicion of assault and controlling or coercive behaviour, while he continues to deny wrongdoing and remains a member of the Senedd.
Thomas announced his resignation on Tuesday, saying he was leaving the leadership position for “personal reasons” after being reported to police over the weekend. He said he had been released without charge and did not want the matter to distract from the work of Reform’s Senedd group.
Gwent Police said a 45-year-old man from the Aberbargoed area was arrested on Sunday 13 September on suspicion of assault and engaging in controlling or coercive behaviour. The force said the man had been bailed pending further enquiries.
Dan Thomas Resigns as Reform UK Welsh Leader
Thomas was appointed Reform UK’s Welsh leader in February and became a prominent figure for the party during the 2026 Senedd election, when Reform emerged as the second-largest group in the Welsh Parliament.
In his resignation statement, Thomas said: “It has been the honour of my life to have been the leader of Reform Wales and see this party go from zero to 34 elected members and become the largest opposition group in Welsh history.”
He continued: “With deep regret, I am now standing down from this position due to personal reasons.”
Thomas also addressed the police investigation directly, saying: “Over the weekend, I was reported to the police and was released without charge.”
Thomas Denies Any Wrongdoing
The former Conservative councillor added: “I stress that I have done nothing wrong, but I do not want the coming headlines to be a distraction from the fantastic work our Senedd team is doing in holding this government to account.”
Thomas said he would remain in the Senedd and continue representing his constituents in Casnewydd Islwyn.
“I will continue to serve my constituents in Casnewydd Islwyn and will fully back whoever the group selects as its next leader,” he said.
His statement means that his departure from the leadership is not a resignation from elected office. He remains a member of the Welsh Parliament while Reform UK prepares to select a replacement.
Police Investigation Remains Ongoing
The circumstances surrounding the arrest remain subject to a police investigation. Gwent Police said the man arrested had been released on bail while enquiries continued.
The distinction between an arrest and a criminal conviction is significant. Thomas has not been charged in connection with the allegations described in the police statement, and he has explicitly denied wrongdoing.
The Independent reported that Thomas said he had been released without charge. Gwent Police, meanwhile, confirmed that the investigation was continuing.
No Charge Announced
The police statement did not identify Thomas by name but described the arrested man as being 45 and from the Aberbargoed area. Thomas is 45 and has been identified in reporting about the arrest.
The investigation therefore remains an unresolved matter, with any further action dependent on the outcome of police enquiries.
Thomas’s decision to leave the Reform UK leadership comes only months after the party made significant gains in Wales and established itself as a major presence in the Senedd.
Reform UK Wales Made Significant Gains
Reform UK entered the 2026 Senedd election seeking to build on its growing support in Wales. The party won 34 seats in the expanded 96-member Welsh Parliament, making it the second-largest group behind Plaid Cymru.
Thomas had been appointed to lead the party in Wales several months before the election and subsequently became the public face of Reform’s Senedd group.
The party’s performance marked a substantial change from the previous Senedd election, when Reform’s representation was much smaller. The 2026 result gave the party a significant parliamentary platform in Welsh politics.
Thomas Had Previously Led Barnet Council
Before joining Reform UK, Thomas was a Conservative councillor and served as leader of Barnet Council in north London between 2019 and 2022.
He later defected to Reform UK in June 2025. He subsequently left his council position and returned to Wales, where he became the party’s leading figure ahead of the Senedd election.
Thomas was born and raised in the South Wales Valleys. His political career has therefore included senior local government roles in England as well as his later return to Welsh politics.
His move to Reform followed a period in which the party sought to expand its presence beyond Westminster and build stronger representation in devolved institutions.
Welsh Labour Responds to Thomas Resignation
Welsh Labour leader Ken Skates reacted to Thomas’s resignation by saying that questions would need to be answered about the circumstances surrounding the development.
Skates told the Press Association: “This is quite incredible news and many questions will need to be answered.”
He also referred to Thomas’s appointment by Reform UK leader Nigel Farage and said: “Dan Thomas was a personal pick by Nigel Farage and this will surely demonstrate the appalling judgment of the Reform UK leader.”
Those comments represent the view of the Welsh Labour leader and are separate from the police investigation into the allegations against Thomas.
The arrest itself does not establish guilt, and Thomas has maintained that he has done nothing wrong.
Sarah Cooper-Lesadd Leaves Reform UK
The leadership change came alongside another major development involving Reform UK in Wales, with Senedd member Sarah Cooper-Lesadd announcing that she had left the party and joined Plaid Cymru.
Cooper-Lesadd, who was elected as a Reform member in May, said she had decided to leave because she believed the party did not match her political priorities.
In a statement reported by The Independent, she said: “Reform has no interest in the work I came here to do. They are not serious about governing Wales.”
She also said the party was more interested in “division, opposition and headlines” than finding solutions, while criticising its approach to vulnerable groups.
Cooper-Lesadd Joins Plaid Cymru
Cooper-Lesadd said she wanted to represent people who had been overlooked and described her approach as evidence-led.
Her move to Plaid Cymru changes the composition of the Senedd following the May election. Plaid Cymru had won 43 seats, while Reform UK secured 34.
The defection means Cooper-Lesadd is now part of the Plaid Cymru Senedd group, adding another political development to an already significant day for Welsh politics.
Her decision was presented as a matter of political values and priorities rather than being directly connected to the circumstances surrounding Thomas’s arrest.
What Happens Next for Reform UK in Wales?
Thomas has said he will support whoever the Reform UK Senedd group chooses as its next Welsh leader. The immediate task for the party is therefore to select a new figure to lead its 33 remaining Senedd members following Cooper-Lesadd’s defection.
The leadership change comes at an important point for the party, which has established a much larger presence in the Welsh Parliament after the 2026 election.
New Leader Will Face Immediate Questions
The next Reform UK Welsh leader will inherit a group that has become one of the most prominent forces in the Senedd but has also faced internal political developments since the election.
The party’s future parliamentary strategy will include its relationship with the Welsh government, its approach to opposition politics and the management of its enlarged Senedd group.
Thomas, meanwhile, is expected to continue as the elected representative for Casnewydd Islwyn while the police investigation proceeds.
His resignation from the leadership does not itself determine the outcome of the police investigation. Any decision about further police or legal action will depend on the continuing enquiries.
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Arrest Does Not Amount to a Conviction
The circumstances surrounding Dan Thomas arrest remain subject to investigation, and Thomas has said he has done nothing wrong.
Gwent Police has confirmed the arrest and bail arrangements but has not announced any charge against him. Thomas has also said he was released without charge.
The political consequences of his resignation are separate from the legal process. Reform UK must now choose a new leader for its Welsh group, while Thomas continues his work as a Senedd member.
The development also comes as Reform UK Wales adjusts to the departure of Cooper-Lesadd, who has joined Plaid Cymru. Together, the two developments have altered the composition and leadership of Reform’s Senedd group within hours.
For now, the central facts are that Thomas has resigned as Reform UK Welsh leader, remains a Senedd member, has denied wrongdoing, and is subject to an ongoing police investigation following his arrest.
