The most senior official at the Foreign Office is leaving his post, after the decision to fail Lord Mandelson's security vetting for the role of US ambassador was overruled by his department.
The BBC understands Prime Minister Sir Keir Starmer and Foreign Secretary Yvette Cooper have lost confidence in Sir Olly Robbins, and he has effectively been sacked.
It comes after the government confirmed the Foreign Office went against the recommendation of the vetting agency and allowed Lord Mandelson to take up the post.
A spokesperson said neither Sir Keir nor any minister were aware Lord Mandelson had failed the vetting process until earlier this week.
Lord Mandelson was announced as the UK's ambassador to the US in December 2024, before in-depth vetting had been carried out, and formally took up the role on 10 February 2025.
