Keir Starmer has said he will lead Labour into the next general election as his Downing Street allies denied claims of any wrongdoing over the appointment and vetting of Peter Mandelson as US ambassador. Darren Jones, the chief secretary to the prime minister, told Sky News’s Trevor Phillips on Sunday show that “no wrongdoing by the prime minister has been proven in relation to Lord Mandelson’s appointment”, adding “the whole situation is regrettable”. Jones said: “Of course these particular questions of whether the prime minister had lied or misled the house, or had done any wrongdoing here that’s all been shown not to be the case.” It has been a bruising week for the prime minister after the Guardian revealed that he appointed Mandelson despite vetting officials recommending that he be denied security clearance. His handling of the row was called into question, including his swift decision to sack the Foreign Office chief Olly Robbins.…