Reform UK Senedd member Sarah Cooper-Lesadd has defected to Plaid Cymru just four months after winning her seat

Reform UK Senedd member Sarah Cooper-Lesadd has defected to Plaid Cymru just four months after winning her seat, issuing a detailed statement that accuses her former party of treating Wales as little more than a platform for Nigel Farage’s UK ambitions.

Cooper-Lesadd, who represents Pen-y-bont Bro Morgannwg, announced on 15 September 2026 that she had left Reform UK and joined Plaid Cymru’s Senedd group. Plaid’s national executive committee approved the move the same day. The switch leaves Reform with 33 seats in the 96-member Senedd and raises Plaid Cymru to 44.

In her statement, Cooper-Lesadd said she entered politics to speak for care-experienced people after growing up in the care system herself. She described her approach as “evidence-led and rooted in what works for our communities.” Reform, she argued, showed “no interest in the work I came here to do” and was “not serious about governing Wales.” The party, she claimed, preferred “division, opposition and headlines” and displayed “a real appetite in the group to want the government to fail.”

She cited specific disagreements, including her wish to support a supplementary budget that she said every party should have backed, and her decision to sit out a debate on Wales as a “Nation of Sanctuary” after speaking about her own childhood trauma. Cooper-Lesadd said she could not support Reform’s “attacks on people seeking sanctuary or other vulnerable groups” or the use of minorities as “political targets.” She added that the party’s Senedd group appeared to exist mainly as “a staging post in the effort to get Nigel Farage into Downing Street,” a focus she said was obvious at Reform’s conference that week.