Newspapers had reported that new president would veto UK pick, as ministers brace for a turbulent four years

Donald Trump will not block the appointment of Peter Mandelson as British ambassador to the US, according to a London-based ally of the president-elect, as ministers brace for a turbulent four years of British-American relations.

Greg Swenson, the head of the UK branch of Republicans Overseas, told the BBC on Sunday he did not believe Trump would prevent the Labour peer from taking up his post in Washington, despite reports to the contrary.