It is just fifty years since a young Middle Westerner, who had been persuaded to go to Princeton by reading Scott Fitzgerald, first arrived in Moscow as an attaché in the newly opened American embassy there. He was already unusually well-equipped to investigate the mysteries of Soviet society. An older cousin – also called George Kennan – had travelled widely in Tzarist Russia and had written about the Siberian exile camps and the pogroms inflicted on the Jews. Young George Kennan himself had already spent five years learning Russian and peering over the fence into Soviet Russia from the then still independent Baltic States.

Kennan was in Russia throughout that cataclysmic reign of evil which we call the Purges. He knew Stalin. In his memoirs he recalled seeing the old dictator’s yellow eyes, ‘like those of an old battle-scarred tiger’, light up with ‘menace and fury’ when he turned on a subordinate unfortunate enough