Yet evidence of the disaster, if not of its scale, has been there for half a century. The numbers escaping from the mainland to Hong Kong at the risk of their lives shot up in the famine years, and as a diplomat in the early Sixties I remember reading reports of our interrogations of refugees recording the horrors of the Great Leap and the brutality of the cadres. Chinese journalists in Hong Kong were on to the refugees too, and told their stories, but in the West not too much was said. In this sense the hecatomb of the Great Leap is comparable to the Holocaust: anyone who wanted to know knew, but many did not.

Denials by sinologues, Maoist sympathisers or "friends of China", many on university campuses, helped to suppress the truth. The same people, or their ideological heirs (as a romantic, highly personalised creed, Maoism has taken on the force of myth, making it impervious to the facts, and so extraordinarily tenacious) will find ways to play down this book, as they did Frank Dikötter's. One is to continue to claim that the deaths were due in the main to natural calamities, a contention that Yang demolishes by detailed reference to the climatological facts of the time. Not even the Chinese Communist Party argues this any more, so not for the first time we have sinologues and leftist Western intellectuals who are more Maoist than the Chinese pope.

A final reason the truth has been long coming is racism. For Western apologists for Mao, China was frequently an abstraction, a plaything of the mind. Many had never been there. Unlike Europeans or Americans, the Chinese were not thought of as flesh and blood individuals, which made the lives of an over-abundant people expendable in the cause of an intellectual experiment. 

Nor were our campus revolutionaries alone. Many a liberal-minded or even right-wing Westerner found and will go on finding excuses for the Great Helmsman's murder of tens of millions of his people. I recently heard of a banker who continues to shrug off the deaths with the comment that in a country that size they were soon replaced. Will the Great Leap Forward ever feature in history lessons in our schools, along with the ubiquitous Nazi studies? For reasons that are ultimately racial as much as political, I think not.