Hitler, mothers, navelgazing: Richard Cork recalls the revealing day he spent with sculptor Henry Moore

By the time I visited Henry Moore in 1981, he had become the most venerated artist in Britain. Major museums and collectors across the world vied eagerly to acquire his bronzes, which often occupied prominent positions in metropolitan settings. At the age of 83, he was in non-stop demand for prestige exhibitions. So when I wrote to him about my fascination with a large, breakthrough carving he had made as a young man, for the Underground Railways HQ in London's Westminster, I expected only a brief letter in response. But to my amazement, he phoned me at once and – without any prompting – invited me to come and see him at home in Hertfordshire.

Although nearly 30 years have passed since I met Moore in his rural retreat, memories of encountering this prodigious octogenarian are still intensely alive in my mind. After catching the train from London to Bishop's Stortford station, on a fresh May morning, I asked a taxi driver to take me to Perry Green. "Henry Moore?" he said immediately with a grin, as if nobody else existed in the entire area. And when we arrived, the driver told me to walk straight in through Moore's front door without even bothering to knock.

Inside, an elderly lady led me to a large conservatory extension at the back. It looked out over fields where unusually white sheep were grazing among the familiar bronze figures. And when Moore came in, I was astonished to discover how small he seemed. His photographs, often showing him in monumental poses beside even more immense sculpture, always suggested an imposing figure. But old age had clearly taken its toll on his physique. Supported by a stick, and wearing glasses that appeared slightly too large for his face, he looked shrunken and quite frail. He wore a cardigan with a prominent blue tie: an odd combination of informality and dressing up for visitors.

The sheer vastness of Moore's international renown might easily have made him seem daunting. But he turned out to be delightfully straightforward, still the no- nonsense Northerner who would abhor any pretentious talk about his art. And throughout our surprisingly lengthy conversation, Moore expressed himself with tremendous gusto and conviction. Almost without my bidding, he started to reminisce about how little sculpture he had been able to see during his youth in Yorkshire.

I soon noticed that, while Moore was talking, his arms and hands never stopped moving. Everything he said was backed up by restless physical gestures – not bombastic but unexpectedly gentle, even feminine. And once, when emphasising how "central" the umbilical area was in his sculpture, he clutched dramatically at the protruding flesh around his stomach. (I was impressed by the sense that everything he said mattered a great deal.) When I asked why the area was so important to him, he answered simply: "Because that's where we were attached to our mothers."

He became especially animated when I got to my point: that powerful carving called West Wind he had made in the late 1920s to adorn the Underground Railways building, opposite St James's underground station in London. Moore asked another grey-haired and hospitable secretary, whom he called Mrs Tinsley, to bring us his substantial 1928 sketchbook for this carving.

While looking through it together, page after fascinating page, I asked whether the many sketches of reclining women marked the beginning of his obsession with this subject. He replied that it may have done, but then launched into a vigorous explanation of how all his work was wholly involved with the human figure, how it was the basis of all our experience, our sense of scale and touch, and how the reclining figure in particular offered a sculptor inexhaustible variations – far more than, say, a seated figure. As Moore talked, I warmed to the passion in this stubborn old man, so animated despite his obvious fragility.

I mentioned Jacob Epstein, who had encouraged the young Moore and urged the architect of the Underground Railways HQ to give him the commission for West Wind. And suddenly, when I cited Epstein's notorious Strand statues, Moore's mood changed to fury. The youthful Epstein had made these nude figures for the façade of a building on London's Strand in 1907-1908, and they were a showcase for his burgeoning talent. But the building was sold in the 1930s, and its new owners hated Epstein's statues so much that they hacked away the supposedly unsafe stonework. The figures were ruined (and are still visible on what is now Zimbabwe House).

Almost half a century later, Moore was still vehement about the Royal Academy's disgraceful refusal to back Epstein in his attempt to stop the tragic mutilation of the Strand statues. "I'll never forgive them for that," he exploded, "nor for the things that Alfred Munnings, the Royal Academy's president, said about my work. He used to carry a photograph of my Northampton Madonna and Child around in his pocket, and show it to people in order to mock it. That's why I'll never exhibit at the Royal Academy. Hugh Casson [the then president] is far more enlightened, but would one ever forgive Hitler in view of what he once did? Fascism may have disappeared on the surface, but what brought it into being will never go away."

Returning to the West Wind carving, Moore told me that Michelangelo helped him to define this airborne woman with conviction. During a trip to Italy in 1924, "I had been very impressed by the flying figures in The Last Judgement, on the end wall of the Sistine Chapel." But Moore also emphasised that he was indebted to the great Toltec-Maya Chac-Mool figure, carved in Mexico during the 11th and 12th centuries. "In my drawings for West Wind I was terrified of going too far towards movement," he told me, "because I don't think carving is much good at motion – it's best at static, weighty, monumental repose."

Nor were his anxieties at an end when he eventually felt ready to start work on the sculpture itself. An enormous three-part slab of Portland stone was delivered to his studio at the Royal College of Art in London. "I did the roughing out there," he recalled, "and it looked so vast that when my future wife Irina came in to see my works, it was one of the things which bowled her over. Then, when it was nearly finished, we put it up on the building. I completed the carving on a scaffolding platform, where there was a space of only about three feet to stand on, and at first I was alarmed. It was so high up! But when I got back down and looked at it from the ground, I realised that the figure's navel couldn't be seen properly. This was terrible, because the umbilical cord is absolutely central to me."

Moore was confronted by a dilemma, because "by this time the scaffolding had been dismantled". But his determination to strengthen West Wind's navel gave him courage. "I went up again in a cradle, winching it up myself from side to side until I reached the carving. But once there, I found that I couldn't carve properly: every time I struck a blow, the cradle shot back from the figure. So in the end I got out some charcoal and shaded the navel in. I knew that it would wash off eventually, and that the navel would by then have darkened with London grime and become prominent enough. The cradle zig-zagged all over the place on the return journey as well. After I'd come down Epstein said: 'I wouldn't have done that for all the money in the world!'"

Moore told me that producing the West Wind relief turned out to be "a valuable experience". Working on an unprecedentedly large scale, between 1928 and the following year, he pushed his fast-developing abilities to a new extreme. The certainty he gained from working on the project contributed to the resounding finality of his great Leeds Reclining Figure soon afterwards, and helped give him the confidence to work on major public schemes. Determined never again to supply reliefs for buildings, he explained that, "I resented the idea that architecture was 'the mother of all the arts'." That is why Moore turned down a later invitation to carve eight seated stone figures on the façade of the Senate House for London University. But he was ready, time and again, to make work in the round for sites positioned near buildings such as the Unesco headquarters in Paris. They satisfied Moore's requirements, who told me, firmly, that, "When an architect simply wants to fill a space he thinks is too empty, the sculpture becomes a decorative thing. I think you've got to have the sense of meeting a sculpture face to face."

While his memory seemed clear, and he was alert and energetic in spirit, maybe Moore suspected that time, for him, was fast running out. He died five years later.

Travelling back to the station, I looked through the cab window and wondered why he had chosen to live in such a notably flat terrain. Moore's sculpture implied that he favoured swollen, craggy forms. But maybe he found the low-lying landscape around Perry Green a relief, after giving shape to all this mountainous abundance in his art.

Henry Moore exhibition, Tate Britain, London SW1, from 24 February (tate.org.uk)