So why does Marx still arouse such admiration — even from centre-Right figures such as Juncker? It is in part a romantic desire to see in him the eternal rebel. The young Karl rebelled against everything: his family, his teachers and the censors. Though proud of his doctorate in philosophy, Marx abandoned an academic career to become an itinerant agitator. Finding Germany provincial, he moved to Paris, got himself expelled, then stirred up trouble in Brussels. Arrested there in 1848, he fled back to Paris, then to Cologne. After being kicked out of both Germany and France, like most Continental revolutionaries he ended up in London. With his lifelong collaborator and benefactor Friedrich Engels (himself a champagne socialist who lived on the proceeds of capitalism), Marx founded the Communist League and later took over the First International, but by his death in 1883 the idea of a Communist party was just that — an idea.

Only in 1848 did Marx find himself in the middle of a real revolution. Convinced that his time had come, he published the shortest (and hence most widely read) of his works: The Communist Manifesto. The celebrated and often paraphrased final words of this pamphlet read: “The proletarians have nothing to lose but their chains. They have a world to win. Workers of the world, unite!” In fact, Marx plagiarised the first sentence from Jean-Paul Marat, the sanguinary French revolutionary who was stabbed in his bath by Charlotte Corday. (It was typical of Marx to side with the tyrant rather than the avenger.) He stole the last sentence from another German journalist, Karl Schapper.

This was not the only example of Marx the plagiarist. “From each according to his abilities, to each according to his needs” was plundered from Louis Blanc, a French socialist. Yet though his prose is often turgid, Marx did have a sinister gift for the chilling phrase. Only he could have come up with “the dictatorship of the proletariat”.

An unforgiving polemicist, he devoted entire books to character assassination. In his letters to Engels, he revealed extreme racial prejudice. For example, he refers to his Cuban son-in-law and acolyte Paul Lafargue as a “n**ger” and his socialist rival Ferdinand Lassalle as a “Jewish n**ger”. Having married an aristocrat, he became a crashing snob, sneering at self-made businessmen while denigrating the underclass as criminals, the lumpenproletariat. He saw no contradiction between his own inveterate sponging and denouncing “parasitical” capitalists who exploited their workers.

Marx was also a domestic tyrant — and a cheat. Having spent all his posh wife Jenny von Westphalen’s money, he expected her to live in squalor with their three daughters in a tiny flat in Soho, above what is now the restaurant Quo Vadis. Their maid, Helene (“Lenchen”) Demuth, devoted her life to the family for no wages — an early example of modern slavery. Marx also fathered a son, Fred, by her, thereby further humiliating Jenny, who was obliged to live in a ménage à trois. Fred and his mother, the only proletarians for whom Marx ever had personal responsibility, received nothing in his will and after his death the whole affair was covered up for many decades. Marxists, it turns out, minded rather a lot about the bourgeois respectability of their hero.