British Deputy Prime Minister Angela Rayner resigned on Friday after admitting she underpaid property tax on a new home, a decision she described as deeply regrettable. The development marks a significant blow for Prime Minister Keir Starmer, who had initially defended her.

After Britain’s independent adviser on ministerial standards ruled that Rayner had breached the ministerial code by failing to pay the correct tax, Starmer said there was little he could do to keep her in government. In a statement, he described her as a “trusted colleague and a true friend,” adding that he was “very sad to be losing you from the government.”

Rayner, 45, is the eighth and most senior ministerial resignation from Starmer’s cabinet since he took office, making it the most damaging departure so far. The case centred on allegations that she had avoided £40,000 ($54,000) in tax on the property transaction.

In her resignation letter to the prime minister, Rayner wrote: “I deeply regret my decision to not seek additional specialist tax advice… I take full responsibility for this error. Given the findings, and the impact on my family, I have therefore decided to resign.” She also stepped down as deputy leader of the Labour Party.

Starmer responded in an emotional letter, saying: “On a personal note, I am very sad to be losing you from the government … Even though you won’t be part of the government, you will remain a major figure in our party.”

The independent adviser concluded that Rayner had broken the code by failing to act on legal advice to seek further expert guidance on her complex financial situation. “It is with deep regret that I must advise you that in these circumstances, I consider the Code to have been breached,” the adviser wrote.

The scandal comes at a politically sensitive time for Labour, which is trailing Nigel Farage’s Reform UK in recent polls. Critics have accused Starmer’s team of hypocrisy over donations and gifts accepted from wealthy backers.