A diplomat in Washington who stood in as interim ambassador after the sacking of Peter Mandelson has abruptly left his post.

In a brief statement, a Foreign Office spokesman said: “James Roscoe has left his post.” No further explanation was officially given on Tuesday night for the departure of Roscoe, who had served as deputy head of mission at the British embassy since 2022.

Roscoe was among those tipped for the top job after the removal of Mandelson over Mandelson’s links to the paedophile financier Jeffrey Epstein. The posting ultimately went to Christian Turner.

As charge d’affaires to the US, Roscoe played a key role in Donald Trump’s state visit to the UK in September 2025.

More recently, as second in charge at the embassy, he was involved in the king’s US state visit to mark the 250th anniversary of American independence.

Before moving to Washington, he was the UK ambassador to the UN and previously served as communications chief to the late Queen Elizabeth II.

He had also been chief press officer in Downing Street for prime ministers Tony Blair and Gordon Brown.

Roscoe’s earlier diplomatic postings included the UN, Sierra Leone and Iraq.