Peter Mandelson’s face appeared at the top of the screen. Below him was Li Keqiang, then the Chinese premier. Ringed around them in the online “Europe-China business dialogue” meeting were top executives from some of the biggest European multinationals. Covid was still rife so the February 2021 gathering took place online, with the British Labour peer in the chair. When a copy of the minutes was leaked, they contained fawning opening remarks from Mandelson about China’s rulers and their ability to “prove [their critics] wrong”. But as Mandelson’s new post as UK ambassador in Washington draws scrutiny of his relationships...