Daniel Johnson: There have been lots of books about Hitler and Stalin, but Mao and Stalin are not so often compared. It might be a good-starting point to look at where these two larger-than-life dictators came from.

Simon Sebag Montefiore: Well, Khrushchev, who knew them both quite well, over quite a long period of time, famously said they were utterly identical.

Jung Chang: Yes, and of course Mao learnt a lot from Stalin — basically how he ran China. His methods, even down to little details — these things he learnt from Stalin. He said Stalin was his mentor, and he meant it.

SSM: As far as childhood is concerned, Stalin really was brutalised by his upbringing. He was beaten by his father out of frustration, and he was beaten by his mother out of love, to discipline him. He grew up in a town dominated by violence, and a culture that worshipped violence. He grew up with that very strange mixture of personal traits which are on the one hand overweening self-confidence and on the other hand a giant inferiority complex and hypersensitivity about his own role.

JC: Mao’s childhood was actually quite an idyllic one. He complained about his father in his later life, but in fact his father was no tyr­ant. I think Mao did have a certain inferiority complex in his early life. He went to Beijing and Shanghai, to those cosmopolitan cities when he was a young man; he wasn’t treated as a star, he was treated as a provincial. But the fact that he had an inferiority complex doesn’t explain his later monstrosity.

SSM: Hitler also was beaten by his father and had an unhappy childhood in that way, but millions of people have unhappy childhoods and bullying fathers and of course most of them don’t become world-historical titans. I think that in the century of Freud we’ve paid much too much attention to the childhoods of these people. Just as important to Stalin, I think, was the conspiratorial underground that he lived in for most of his formative years, from 18 years old; and also hugely important with him was the education of the Church.