Peter Mandelson’s appointment as Britain’s ambassador to the United States continues to cast a long shadow over Keir Starmer’s government, with a newly released tranche of official documents revealing sharp private criticism of both the prime minister and his Downing Street operation.

British Prime Minister Keir Starmer faces more embarrassment with the release of files about former U.K. ambassador to Washington Peter Mandelson.

British Prime Minister Keir Starmer faces more embarrassment with the release of files about former U.K. ambassador to Washington Peter Mandelson

The release revives a controversy that has dogged Starmer's government since reports emerged about Mandelson's past links to the late financier and convicted sex offender Jeffrey…