A statue of Adolf Hitler was unveiled in Manchester yesterday. Local artists attended the opening, some of them wearing Nazi insignia. "Of course we don't agree with everything that happened in the Third Reich", said one of the organisers. "But Adolf was a great connoisseur of architecture. He was so fond of Manchester's Midland Hotel that he ordered the Luftwaffe to spare it during the Blitz".

All right, I have played a little trick on you. It wasn't Hitler who was celebrated in lapidary form in Manchester. It was Friedrich Engels who, with Karl Marx, co-authored the Communist Manifesto. Engels moved to Manchester, where his father owned a factory, in 1842. One of the paradoxes of Communism is that Engels used some of the profits from that factory to support Marx – a notorious cadger who never properly worked for a living, and never set foot in a factory himself.

Ah, you say, but that's different. Hitler was a criminal and a murderer, whereas Engels was a political theorist – maybe a misguided one, but hardly in the same moral category as the Nazi dictator.

As far as we are aware, neither Hitler nor Engels personally murdered anyone. Both, however, engendered millions of deaths. Indeed, measured by the grim calculus of slaughter, Communism must be reckoned the most destructive ideology of all time. Nazism killed 17 million people; Communism 100 million.

Of course, the human brain can't visualise such numbers. We can try to picture individual victims – dragged from their beds to torture chambers, shot into pits, worked to death in the gulags, starved as deliberate policy to enforce collectivisation – but we can't begin to take in the scale. Still, it's worth repeating. One hundred million deaths. And someone thinks it's clever to raise a statue to the man who got the whole thing started.

A statue of Friedrich Engels was unveiled today in Manchester, where he lived and wrote 'The Condition of the Working Class in England'. pic.twitter.com/hObLTS3nRB — Jacobin (@jacobinmag) July 16, 2017

At this point, a bizarre double standard enters into play. The Nazis implemented their own doctrine. In pursuit of National Socialism, they plunged Europe into war, plundered and enslaved whole populations and, in the end, carried out a deliberate genocide. We can all agree that they were evil.

But Marxism is somehow judged as a textbook theory, unrelated to its real-world outcomes. Nazism led to people being categorised and murdered en masse, and everyone can now see that that was wrong. But the fact that Communism led to similar outcomes is somehow regarded as an aberration.

Marxism is somehow judged as a textbook theory, unrelated to its real-world outcomes

In fact, every Marxist regime ends up being homicidal. Tens of millions died in the Soviet Union and China. There were torture chambers, labour camps and firing squads in every Communist country, from Cuba to Vietnam, from Albania to North Korea.

You didn't have to be an opponent of the regime to be shot. Your crime might be having the wrong parents, or holding a university degree, or attending church. In Communist Cambodia, wearing glasses was enough to condemn you to death: it was taken as a sign that you spent too much time reading instead of working with your hands.

All these regimes were fulfilling their foundational ideology. Marx and Engels taught that the end justified the means, that human beings were not individuals with their own hearts and souls, but machines – or, rather, cogs in the great machines that made up the social classes. If someone needed to be eradicated in the cause of progress, the good Marxist should order the eradication coldly and scientifically. You couldn't make an omelette without breaking eggs.

Not that the omelette ever emerged. By 1990, the broken eggshells were everywhere, but there had not been a single example of a successful Marxist regime. Not one. All of them ended up being squalid and miserable as well as lethal.

Yet we pretend that the fox-hunting, sybaritic Engels had nothing whatever to do with the abominations carried out in his name. Jeremy Corbyn and John McDonnell still regard Marxism as a doctrine that is somehow theoretically correct, even though they cannot point to a single example of its actual success. And, horrifyingly, a chunk of the country appears to be going along with them.

Daniel Hannan has been Conservative MEP for the South East of England since 1999, and is Secretary-General of the Alliance of European Conservatives and Reformists. Follow : @danieljhannan