There is a story, apocryphal perhaps, about the meeting between John F. Kennedy and the Soviet leader Nikita Khrushchev in Vienna in June 1961. At one stage, the discussions became quite heated, with the President exclaiming, ‘Do you ever admit a mistake?’ ‘Certainly’, replied Khrushchev, ‘In a speech before the 20th Party Congress, I admitted all of Stalin’s mistakes.