Conservative MP Suella Braverman - a former Home Secretary - has defected to Reform UK.
Her defection was announced at a rally for activists in central London where party leader Nigel Farage greeted her on stage.
The news comes as Nigel Farage is reported to have said that UK military veterans convicted for their roles during the Troubles in Northern Ireland would be pardoned under a Reform UK government.
The party leader promised to end current prosecutions of British veterans, through legislation or the royal prerogative of mercy, and to stop future legal action, according to The Daily Telegraph.
"We are proud to be launching our veterans wing. We will fight the injustice being done to our former servicemen and stand up for their rights," he told the newspaper.
A Reform policy document, seen by the Daily Telegraph, reportedly states that the party would "legislate for a statutory bar to end current and prohibit future proceedings against British veterans for historical conduct".
It added: "This will draw a line under a situation where terrorists have faced no consequences for their heinous actions whilst veterans have been unfairly hounded.
"British forces were responsible for a small proportion of deaths during the Conflict in Ireland from 1969-1993 (approximately 11%), and yet the vast majority of the 30 potential inquests into Troubles related killings and around 600 civil cases in the pipeline involve the actions of lawfully deployed British security forces."
Earlier this month, MPs voted on a British government remedial order to remove protections giving immunity from prosecution to anyone accused of crimes during the Troubles if they provide information to a truth recovery body.
This was part of the previous Conservative government's Legacy Act which was approved in 2023, but the High Court in Belfast ruled parts of the Act were incompatible with the European Convention on Human Rights (ECHR) in 2024.
The Reform police document added the pledge to bar future prosecutions and pardon old convictions would match "what was given to the IRA under [former Labour Prime Minister Tony] Blair; they were released from prison, pardoned or given comfort letters, and even allowed to engage in front-line politics".
UK Shadow armed forces minister Mark Francois said the Conservatives have been "defending those who defended us" for "years".
"As someone who has campaigned consistently on this issue for almost a decade, I welcome support from other parties, even belatedly," he said.
"However, the Conservatives have voted repeatedly in parliament to oppose Labour’s assault on our 2023 Legacy Act," he added.
As it currently stands, the Legacy Act offers immunity from prosecution to anyone accused of crimes during the Troubles in Northern Ireland if they provide information to a truth recovery body.
While the Legacy Act was approved in 2023, it was not enacted.
The then-Conservative government began the process of appealing against the High Court decision, but this was dropped by Labour ministers after the 2024 general election.
More than 3,500 people died during 30 years of bloodshed in the North, which began in January 1969 when the UK government deployed troops to Northern Ireland.
