By my reckoning, yesterday will be remembered as perhaps the most difficult of Sir Keir Starmer’s premiership yet, with even close allies telling me they are not sure where it will end. His admission at Prime Minister’s Questions that he knew of the friendship between Peter Mandelson and Jeffrey Epstein when he appointed him as US ambassador hardened the sentiment of many a Labour MP who was willing to give him the benefit of the doubt. Insiders tell me that changed when Starmer told the Commons that security vetting had confirmed the continued friendship between Mandelson and Epstein after the financier was jailed for child prostitution offences, leaving MPs furious at the prime minister and his aides for allowing the ex-Labour minister back into the heart of government. Some MPs consider this an unforgivable lapse of judgement. Image: Starmer faced perhaps his toughest PMQs to date. Pic: Reuters Number 10 has compromised on the release of files relating to Mandelson’s appointment. It will now be for the independent Intelligence and Security Committee, and not the …