Unelected and unaccountable, the former US ambassador and ‘party stirrer’ nonetheless took it upon himself to make all party business his own, waspishly whittling away at Starmer’s authority – which makes the PM’s appointment of him all the more bone-headed, says Sean O’Grady T he usual reason, or excuse, put forward at the time for making Peter Mandelson ambassador to Washington and de facto senior factotum to Keir Starmer was because, in the words of Peter Kyle, Mandelson’s “singular talents”