Sir Keir Starmer remains under pressure over his handling of the Lord Peter Mandelson scandal but the intense scrutiny on his trusted chief of staff saw him resign from his post.Morgan McSweeney, seen as an ally of the disgraced peer, was considered the driving force behind Mandelson’s appointment as US ambassador despite knowing that his dealings with paedophile Jeffrey Epstein continued after the financier’s conviction for child sex offences.As the Prime Minister’s right-hand man, Mr McSweeney was in charge of strategy and central to decision-making at the heart of Government.