Police investigating the theft of a phone belonging to Keir Starmer’s former chief of staff Morgan McSweeney have arrested a man. The man, who was arrested on Wednesday in Peckham, south London, is suspected of receiving the phone after it was stolen, the Metropolitan police said on Thursday. The government-issued iPhone, which was stolen shortly before 22.30pm on 20 October last year, has not been recovered. Concerns have been raised that the theft could result in important messages about Peter Mandelson’s appointment as ambassador to the US being lost. The whereabouts of McSweeney’s messages with Mandelson has been under intense scrutiny since it was reported that the work device was stolen shortly after Mandelson was sacked as US ambassador. It was revealed in March that McSweeney did not disclose that he was Starmer’s chief of staff when he reported the theft of his phone . The Met released a transcript of the call, a highly unorthodox move, saying it wanted to correct misreporting of the incident.…