Stalin famously said, midway through the Second World War, that when the fighting was over, whoever occupied a territory ‘would impose their own social system on that territory … it can be no other way’. Every now and then the monster called things right. The western Allies introduced liberal democracy into states often unfamiliar with it, promoting free markets and independent legal systems. In western Europe, through choice, people have stuck with the democratic idea, however imperfect, ever since.

In the East, the victorious generalissimo imposed his version of communism, based partly on ideology and partly on his mistrustful and secretive personality. How Stalin and his apparatchiks colonised and crushed all opposition in a third of Europe is the subject of Anne Applebaum’s brilliant and important book, as masterly