JK Rowling has launched a blistering attack on “coward” Sir Keir Starmer after his U-turn on trans rights. The Prime Minister backtracked on his previous claim that “trans women are women” after a landmark Supreme Court judgment.

Sir Keir, who once suggested some women can have penises, declared that a woman is an “adult female”. In a post on X, the Harry Potter author said: “Imagine being such a coward you can only muster the courage to tell the truth once the Supreme Court has ruled on what the truth is.”

It comes after the UK’s top court last week ruled that the terms “woman” and “sex” in the 2010 Equality Act “refer to a biological woman and biological sex”.

Breaking his silence on the judgment, Sir Keir said he welcomed the Supreme Court’s ruling.

Asked to repeat his previous statement that “trans women are women”, he said: “I think the Supreme Court has answered that question."

Pressed if that means he does not believe a transgender woman is a woman, he told ITV West Country: “A woman is an adult female, and the court has made that absolutely clear.

“I actually welcome the judgment because I think it gives real clarity.

“It allows those that have got to draw up guidance to be really clear about what that guidance should say.

"So I think it's important that we see the judgment for what it is. It's a welcome step forward.

"It's real clarity in an area where we did need clarity, I'm pleased it's come about.

"We need to move and make sure that we now ensure that all guidance is in the right place according to that judgment."

Downing Street confirmed the Prime Minister's U-turn from his earlier position.

Asked if Sir Keir still believed that a transgender woman was a woman, the Prime Minister's official spokesman said: "No, the Supreme Court judgment has made clear that when looking at the Equality Act, a woman is a biological woman.

"That is set out clearly by the court judgment."