Anthony Powell would purr if he could read this shrewd, fond biography by Hilary Spurling

The novelist Anthony Powell polarises people – and this partisan biography is firmly in the 'genius' camp. He would have agreed, says Nicholas Shakespeare

Nothing provoked more violent argument in the autumn of 1957, observed a contemporary commentator, than "the Suez crisis and the novels of Anthony Powell". The latter could divide a dinner table "with the sudden fierceness of a civil war". On one side ranged those who considered A Dance to the Music of Time, then four volumes old, uneventful, colourless and snobbish; on the other, those who in Hilary Spurling's words "recognised [in it] the tone and texture of life itself".

This argument has never, so far, been resolved, just as for every person who regarded the author in the flesh as "strikingly good-looking", there rose another who viewed him, like Philip Larkin did, as "a horse-faced dwarf ". It has not helped his cause that Powell himself was similarly Manichean, dividing the world beating a path to his door at The Chantry, his house near Frome, into Fans (the word "fan" appears on virtually every page of his journals), and Shits.

Fans were those who had read and admired his work – to the exclusion of all else in the case of Miss Nancy Cutbirth of the AP Society, Kalamazoo – and were embarked on a bibliography, biography, thesis, or 12-part adaptation of his work. Among the Shits were those journalists and bearded photographers who arrived, invariably late, to interview him about it.

Although a distinguished book critic himself, not least for these pages, Powell held journalists in the same regard as reviewers ("stupid, incompetent, often envious, rarely grasping the point of any given book"). Private Eye parodied his posture like this: "20th January 1995. Re-read various fan letters confirming that I am the leading novelist of my generation. Why is it, one wonders, that my fans are so unusually percipient? Re-read Hamlet by Shakespeare, a competent but unreliable author, though by now rather dated and always prone to worthiness. Never to my knowledge managed a novel."

Not normally a writer to stand one's hair on end, Powell does so when contemplating his fellow practitioners. His publishers used to categorise him as "probably the greatest living English writer", which made him sound like a lager. But just look how actively he cleared the ground of rivals past, present and future. The effect is not unlike napalm.

Gustave Flaubert: "Does rather pile on the agony at the end."

Graham Greene: "Absurdly overrated."

Evelyn Waugh: "Unnourishing feeling in most of his books."

Vladimir Nabokov: "Appallingly third-rate tinsel stuff."

Gabriel Garcia Márquez: "Rot." Salman Rushdie: "Characteristic of particular sort of bad writing."

Julian Barnes: "Can't quite see the point."

What continues to make Powell's own reputation hard to assess is the curious disruptive enzyme in his make-up that provoked several of his closest friends and supporters like Malcolm Muggeridge (they were so close they were mistaken for brothers) and VS Naipaul (whom Powell championed from the start, as he did many others) to transmogrify suddenly from Fans into Shits. Muggeridge's defection was breathtaking. He had walked daily with Powell in Regent's Park, plotting Dance together, only later to launch a savage attack, which Powell never got over, complaining about its "inner drabness" and "snobbishness", and suggesting that posterity would judge it as "a heap of dust".

If this betrayal was bad enough, it was small beer when compared to Naipaul's volte-face. Having written unctuously to Powell that his language contained "the wonder and magic of a sonnet by Shakespeare", Naipaul revised his opinion after a "serious connected reading of his work". Experiencing an "Ibsen-like horror", Naipaul was "appalled". Powell's entire 25-year project was "the acme, the height, of mediocrity".

Hilary Spurling, also late of these pages, is a steadfast Fan – reading Dance, on which she has published an index, "changed my life". She first met Powell in 1969. He swiftly became "a captivating friend", while he considered her "far the best reviewer I know". Like Christopher Sykes's biography of his friend Evelyn Waugh, her Anthony Powell is shrewd, affectionate and clear-sighted.

"The last thing on earth I should like is to be young again," wrote Powell. Spurling paints the picture of an insular only child of a malevolent army father – plus splenetic grudge-bearer – and a doting neurotic mother who was old enough to be his grandmother. Left to his own devices, Powell became as self-contained as a biscuit tin, obsessed by toy soldiers, antiquarian books and genealogy; his last move before resigning from Duckworth's, where he worked after university as an editor, was to order Burke's Landed Gentry on trade terms.

His first permanent address was his private school. Eton "indelibly marked" Powell, being the earliest community to accept him. He fagged for David Cecil and was in the same house as Hugh Lygon, the model for Waugh's Sebastian Flyte. By contrast, the Oxford of Brideshead Revisited was a colossal let-down: "How little I liked being at Oxford." Aged 20, Powell lost his virginity to a prostitute in Paris. There, he also met the artist Nina Hamnett, a displaced army child like him, who became "his bohemian mistress".

Back in London, Hamnett introduced Powell to her raffish émigré circles in Fitzrovia where he embarked on his "de-Oxfordification", as he called it. Shedding literary Eton/Oxford friends like Henry Yorke, he took up with the avant-garde artists who from now on shaped what Spurling identifies as Powell's "essentially pictorial" response to the world: the composer Constant Lambert, the painters Edward Burra and Adrian Daintrey, the art historian Gerald Reitlinger, figures who would resurface in Dance - which, one might say, is no more or less a dramatisation of "the heterogeneous interlocking circles of Tony's friends".

Prone to depression ("my awful bag of gloom"), with little money (Duckworth's paid £5 per week), and not much income from writing (Spurling discreetly avoids numbers, but Penguin gave "poor sales" as the reason for its £300 advances), Powell never achieved what Spurling nicely calls "the almost fairy-tale arrival of overnight celebrity". He was 45 before he started, in 1950, on the novel sequence that was to make his name, henceforth pronounced as Pole.

Spurling, biographer of Matisse, is at her sympathetic best when explaining the influence on Powell's work of artists like Bruegel, Tiepolo and Poussin – whose eponymous painting in the Wallace Collection provided the kick-start for the 12-novel series which caused Powell to become known in Paris as un Proust Anglais. The brocaded collage that is Dance – a continually shifting tableau of "human beings behaving" – is still nowhere better conveyed than by Evelyn Waugh, in his image of Powell's characters as fish in a glass tank who one after another swim towards us. "We see them clearly, then in a barely perceptible flick of fin or tail, they are off into the murk."

The rest of his life is uneventful, a compendium of Swan Hellenic cruises and country house weekends. Like Poussin and another big influence, John Aubrey, Powell retired to the country to compose his canvas. There he could be discovered with his wife Violet ("the right arm" of his imagination, their son Tristram called her), reclining on an elderly chaise longue as he pondered and processed his epic – "like Mme Récamier," in Ferdinand Mount's evocative glimpse, "with a favourite cat strolling impertinently across his cavalry twill trousers".

Powell would have approved of this biography, which puts him unfailingly in his own best light. The nit-picker in him might have pointed out that Cascais is not "on the rocky southern coast of Portugal" but near Lisbon, and that his former regiment is preferably spelt Welch. Yet he would have purred like his cat Fum at the way Spurling has brought him to humane and generous life, made head and tail of his character and work, and begun the process of restoring Powell to the same shelf as his contemporaries like Waugh, Greene and Orwell, where he always felt he belonged anyway.

ANTHONY POWELL by Hilary Spurling
528pp, Hamish Hamilton, £25, ebook £12.99. To order a copy from the Telegraph for £20, visit books.telegraph.co.uk or call 0844 871 1514

Nicholas Shakespeare's Six Minutes in May: How Churchill Unexpectedly Became Prime Minister is published by Harvill Secker