Photo by Leon Neal/Getty Images Morgan McSweeney, the former chief of staff to the Prime Minister, has just finished speaking at the Foreign Affairs Select Committee. He was grilled for over two hours about the decision to appoint Peter Mandelson as British ambassador to the United States, over which he resigned in February. Here are seven things we learnt from the session. He regrets the Mandelson affair Morgan McSweeney began this rare public appearance with a statement of contrition. He said that his advice to the Prime Minister to appoint Mandelson as ambassador was a “serious error of judgement” and that his resignation from his No 10 chief of staff role was evidence that he had taken responsibility for that. Later in the hearing, he said that, when the Bloomberg story showing further evidence of Mandelson’s involvement with Epstein appeared in September, “it was like a knife through my soul”.…