James Roscoe, Britain’s second most senior diplomat in Washington, has abruptly left his post. The UK government provided no reason for his sudden departure, which comes amid an investigation into the leak of discussions at a meeting of the UK’s national security council.
Roscoe had served as deputy head of mission at the British embassy since 2022 and stood in as interim ambassador after the sacking of Peter Mandelson. He was among those tipped for the ambassadorial job, but the posting ultimately went to Christian Turner.
Senior officials at the embassy are said to have been questioned as part of an investigation after reports this year of cabinet splits at a national security council meeting over allowing the US to use British bases for strikes against Iran. The leak is considered a serious breach of the Official Secrets Act.
David Lammy, the justice secretary, ordered the investigation. The Spectator reported that Keir Starmer suggested allowing the US to use the bases for defensive strikes against Iranian targets, but faced opposition from Ed Miliband, Rachel Reeves, Yvette Cooper and Shabana Mahmood.
As chargé d’affaires to the US, Roscoe played a key role in Donald Trump’s state visit to the UK in September 2025. He was also involved in King Charles’s state visit to the US for the 250th anniversary of American independence.
Before Washington, Roscoe was UK ambassador to the UN and served as communications chief to Queen Elizabeth II from 2013 to 2016. He also worked as chief press officer in Downing Street for Tony Blair and Gordon Brown.
