In Robert Harris’s alternative history, Fatherland, the Allies lose the War, and a “reformed” Nazi party rules an apparently peaceful and orderly empire. Its past crimes have been carefully erased from public memory. If such a scenario seems preposterous, bear in mind that that’s almost exactly what has taken place in China.

The current Chinese regime is still the same one responsible for the Great Leap Forward – “the biggest episode of mass murder in the history of the world” – and the Cultural Revolution. The architect of both enormities is still venerated throughout China. Which is no different than if Hitler’s image still dominated Europe’s public spaces.

The communist government of China turned 70 on Tuesday. It is the most powerful and almost the longest standing communist regime in history. Any assessment of Chinese communism must start by recognising the fantastic economic progress of the past four decades that has lifted hundreds of millions of people out of poverty.

But let’s take a step back to look at communism, specifically Chinese communism. For a start, China’s economic development since 1979 has owed absolutely nothing to communist ideology.

“Socialism with Chinese characteristics” is simply a euphemism for a corporatist economy dominated by an all-powerful, brutal state. Which sounds an awful like Fascism, to be honest.

Some pro-Beijingers hold that the communist element of the Chinese Communist Party no longer has any significance. This is not the view of President Xi Jinping, nor of any Communist Party organisations, or indeed of most consequential Chinese.

The political zeitgeist in the West is always on the brink of panic that extreme right-wing ideology is poised to triumph somewhere. In fact, right-wing ­extremism was destroyed as a political force in the mid-20th century and happily has never recovered, except in the wildest fringes.

Left-wing extremism, on the other hand, is the official ideology of ­numerous ruling parties in several parts of the world. Here we must realise that Marxism was ­intrinsically one of the most evil ideologies that humanity has ever invented. It is the twin of Nazism, though it killed more people in the 20th century than Nazism did.

Marxism, Nazism and Fascism are all the bastard children of Socialism.

Everything about Marxism was evil or ridiculous, or both. Every word of it was a lie. Its ideas were absurd and never described any existing reality nor ever predicted any emerging reality. The Chinese communists did not come to power through a revolution of the proletariat as Marx and his successors envisaged. Indeed Marx’s perfectly nonsensical theory of the Asiatic mode of economy was ­embarrassing when he wrote it and bears no relation to anything that has ever happened in China.

Apologists invariably hand-wave away the crimes of Communism as somehow solely due to Stalin or Mao – which is as ridiculous as arguing that the Holocaust was only Hitler’s fault, because “that wasn’t real Nazism”.

But, hand-wave as they will, the raw fact remains that everything Stalin and Mao did – from gulags, purges, mass torture and killing, to engineered famine – had already been initiated by Lenin.

The key figure in the historic development of communism was not Marx, or Mao Zedong, or Stalin, but Lenin. The Chinese Communist Party is best understood as a Leninist party. Lenin’s central contribution, both intellectual and programmatic, was his ruthless understanding of how to seize and retain state power.

This is the true heart of all communist ideology — the ruthless pursuit and maintenance of power….While the modern Chinese leadership has certainly reversed many communist economic policies, it has never reduced its fidelity to Leninism. If anything, Xi’s ­removal of term limits, reduction of institutional legalism, downgrading of traits of collective leadership and increased oppression of religious and ethnic minority groups and legal rights lawyers is a purer expression of Leninism than the cautious political reform of his recent predecessors.

The first three decades of communist rule in China were an ­unmitigated disaster…Marxism is so perfectly useless and irrational in its economic ideas that whenever a communist government tries to implement it, as Mao did…it fails disastrously, at terrible human cost, and is eventually abandoned.

No-one would for an instant tolerate a “reformed Nazi party”. Any academic who claimed to advocate “real” Nazism would rightly be sacked in disgrace in an instant. Yet Communism is allowed to fester on, and everyone politely pretends not to notice.

Communism was an unmitigated disaster for all humanity. Regimes that proclaim it still are inherently problematic.