Former U.K. Ambassador to the U.S. Peter Mandelson said Sunday he had resigned his membership of the Labour Party to avoid causing “further embarrassment” over his friendship with the late convicted sex offender Jeffrey Epstein. Mandelson’s decision to quit the party came after new documents released by the U.S. Department of Justice on Friday appeared to show that Epstein made payments amounting to $75,000 to accounts linked to the Labour peer between 2003 and 2004. Mandelson, who was a Labour