Keir Starmer says it is âstaggeringâ and âunforgivableâ that he was not told Peter Mandelson had failed security vetting before taking up the role of US ambassador. The comments follow a Guardian investigation that exclusively revealed Mandelson had initially been denied clearance after a background check by security officials, but that the decision was overruled by the Foreign Office. Lucy Hough speaks to the Guardianâs head of investigations, Paul Lewis â watch on YouTube. Help support our independent journalism at theguardian.com/infocus