‘Together with the Germans’, Stalin is alleged to have remarked, ‘we would have been invincible.’ For just under two brief years between August 1939 and June 1941 they were together, bound by an uncanny alliance forged on the eve of the Second World War. The British and French were not surprised. Their prejudice against the Soviet Union coloured their belief that the two dictators were as bad as each other, and not such strange bedfellows after all.

The subsequent German invasion of the Soviet Union in Operation Barbarossa in 1941 made Stalin a temporary ally of the West. Yet while the Grand Alliance of Britain, America and the Soviet Union that gradually emerged during the war placed the earlier collaboration between the two dictatorships into the shadows,