Do you know the one about the Englishman, the French­man and the New York Jew of Polish extraction who lived in Britain and who was involved in a couple of the noisiest art scandals of the early 20th century? Me neither — until the Royal Academy decided to yoke Eric Gill, Henri Gaudier-Brzeska and Jacob Epstein together and present them to us as a fateful modern-art threesome who changed the course of British sculpture.

The academy has given its display the overall exhibition title of Wild Thing, which I initially as­sumed was an inappropriate quotation from the Troggs. It turns out, instead, to have been something Ezra Pound once said of the young Gaudier-Brzeska. A “bright-eyed wild thing”, he called the baby Frenchman with the enormous talent; “a well-made young wolf”. The title refers well enough to the spirit of all of them.

All three were strangers to normal behaviour. All three were chiefly stone carvers, for whom the act of creation took place in a spray of rocks and chippings. All three managed to force British sculpture out of the 19th century and into the jet stream of the modern age. What their relationship was not was a partnership of equals.

The ridiculous Eric Gill, so quintessentially English in his refusal to complete the transfor­mation from vicar to artist, never became a truly modern sculptor. The show gives each of its pioneers a section to themselves. Gill’s is the weakest. His starting offence is a snake-hipped and feeble Christ, carved in 1909, who hangs so timidly on the cross that a purr from a passing kitten might frighten him. Gill gives his timid Jesus the genitals of a one-year-old boy, and a matching inscription in ancient Greek: “Some eunuchs were born from their mother’s womb; some eunuchs were made eunuchs of men; and some eunuchs have made themselves eunuchs for the kingdom of heaven’s sake.” Which translates as: Christ became a eunuch to save us.

It’s the thinking of a crackpot. Ever since Fiona MacCarthy published her eye-watering biography of Gill, I have been entirely unable to take the man seriously. It is not only the incessant incest with his sister and the terrible abuse of his children, the penetrated maids and the sex with his dog. What really jars about Gill, what makes the stomach heave, is the appending of his grotesque libidinousness to religious art.

While the first half of his display is devoted to frenzied scenes of sexual abandon — the sculpture now known as Ecstasy was originally titled F***ing — the second half becomes relentlessly about the mother and child, with statue after statue showing a Madonna suckling her baby. How a man who was habitually abusing his prepubescent daughters could make this much art about the innocence of Mary and Jesus is beyond my human ken. What I can see and comprehend is Gill’s instinctive kitsch­­ness: the absence of real sculp­tural invention in his work; the happy-clappy wanness of his touch. In life, he may have been a sick wild thing, but in his art he was merely a watered-down pre-Raphaelite.

Thus, the exhibition proper, the real sculptural achievement, commences with the arrival in Britain of Henri Gaudier-Brzeska Originally from Orléans, Gaudier was an extraordinarily precocious genius — yes, genius — whom history decided to toy with cruelly. He arrived here in 1910, aged 19. By 1915, he was dead, killed on the western front. Into those few precious years, he squeezed a sculptural career of unusual brilliance and vigour.

Modernism was young. Gaudier was young. And the two of them exploded into action like synchronised swimmers. The first figure we see by him, The Wrestler, from 1912, is a bulky, bovine brute of a man, fashioned, unusually, from pure lead, who sways towards us at a dangerously unstable angle, as if he is reaching for our ankles. After the pretend primitivism of Gill, here is the real thing, driven by the core sculptural understanding that the relationship of a human being to a sculpture is, in the end, one lump encountering another lump.

In a mere year or so, the 20-year-old Gaudier turns himself from a wonky self-taught sculptor into a sophisticated artistic adventurer, quoting easily and knowingly from enough international styles to fill the British Museum. Indeed, that is where most of his influences were encountered. The utterly lovely Red Stone Dancer combines Indian gracefulness with Aztec geometry. How superb, too, that the show contains his waist-high head of Ezra Pound, whose features have been cubistically simplified in order to enlarge their unmissable resemblance to a large stone penis.

Both Gaudier-Brzeska and the dreaded Gill owe their preference for stone carving to the example of Jacob Epstein, who pioneered the method in Britain. Epstein, who arrived here in 1905 from New York’s Lower East Side, via Paris, is another deeply irritating artist. Unlike Gill, he had talent aplenty to go with lashings of sexual craziness. Yet he, too, seemed weirdly incapable of telling the difference between genuinely moving art and kitsch. His mating doves, gathered here in a row of white marble caricatures, are far too cooey for the reduction of their outlines to feel like proper streamlining.

Elsewhere in Epstein’s portion of the show, though, he reveals himself to have been a potent and exciting sculptor with a classic modern-art talent for causing rumpuses. In 1908, he carved some nudes for the facade of the British Medical Association, and the so-called Scandal in the Strand blew up. “A form of statuary which... no discriminating young man [would wish] his fiancée to see”, screamed the front page of the Evening Standard. The furore ended with a group of fabric inspectors going up there with hammers and knocking off the offending bits.

Yet when Epstein’s tremulousness and his talent get into step, the results can be awesome. The most stirring sight at this exhibition is surely that giant piece of wayward sculptural invention known as The Rock Drill. It was made in 1913. Yet something of the barbarity of the terrible war ahead managed, mira­culously, to seep back into it.

Taking a rock drill of the kind used in the gold mines of South Africa, Epstein attached a creepy mechanised form to it, half human, half machine. This robotic monster operates the drill with madly phallic thrusts. The Rock Drill is probably the single most inventive piece of sculpture to be made in Britain. These days, after all those episodes of Star Wars, the straddling man-machine has a familiar intergalactic alienness to it. But imagine encountering him in 1913, a mere decade after the first flight of the Wright brothers. Astonishing.

Wild Thing is at the Royal Academy, W1, until January 24, 2010

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