It suited Western Leftists, during and after the War, to argue that Hitler had been uniquely evil, certainly wickeder than Stalin. It was thus necess… - Daniel Hannan

Eugenics, of course, topples easily into racism. Engels himself wrote of the "racial trash" - the groups who would necessarily be supplanted as scientific socialism came into its own. Season this outlook with a sprinkling of anti-capitalism and you often got Leftist anti-Semitism.

Don’t get me wrong. Every atrocity is unique in its own terrible way. The Nazi Holocaust haunts us for good reasons. Years after I saw it, I still find this image rising, unbidden, in my mind. Happily, though, no one, beyond a deranged fringe, denies the nature of Nazism. The same is not true of the Soviet tyranny.

The coincidence in doctrine between the Nazis and the Soviets was obvious to the “decadent” Anglo-Saxons, too. The day after the Soviet invasion of Poland, a Times editorial observed that “Only those can be disappointed who clung to the ingenuous belief that Russia was to be distinguished from her Nazi neighbour, despite the identity of their institutions and political idiom, by her foreign policy”.