During the last century, England produced three great Catholic novelists: Graham Greene, Evelyn Waugh and Anthony Burgess. Unlike the others - both converts - Burgess was a cradle Catholic turned apostate. He was also more prolific, a modernist in the Joycean sense, and of humbler origins: grammar school and provincial university, both in Manchester, rather than public school and Oxford. Like Greene, much of his life was spent in exile; like both Greene and Waugh, he was haunted by the idea of Original Sin, and often his writing assumes a confessional mode.

Autodidact, polymath and musician as well as writer, Burgess had an early vocation of teaching which never left him. Like that other pedagogue, lapsed Catholic and expatriate, James Joyce, he was fascinated by "the miracle of the language" and eager to give it new form and expression. And Joyce, together with Shakespeare and Lawrence, were his most enduring influences. He emulated them and wrote celebrations of them: two books, a screenplay, a musical and a ballet suite in Shakespeare's case, three books and a musical in Joyce's.

Gore Vidal considered him better than Joyce, but Joyce was more focused and avoided having to write for a living. Burgess's scattergun approach and readiness to offer his pen for hire weakens the comparison. Furthermore, unlike Joyce, he was never wilfully obscurantist, and while Joyce became reclusive, Burgess happily sought the media spotlight: Arena, Parkinson and Wogan all found him a willing performer. But he shared the Irishman's attachment to an abandoned Catholicism, his taste for exile and a determination to exist by his own cunning.

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He preached against sloth and was, said William Boyd, possessed by a "prodigious fecundity". Writer's block never visited him. He reeled off a daily 1000 words before lunch, producing over 30 novels, operatic libretti, guides to literature, translations, coffee-table books, acres of journalism, endless book-reviews, and umpteen screenplays. On top of that, he turned out symphonies, concertos and film scores "like knitting", he said.

From his 1950s Malayan trilogy through A Clockwork Orange (his notorious take on Crime and Punishment with its marauding Droogs, concocted slang, and Orwellian brainwashers), to his monumental Earthly Powers, and two-volume Confessions, there is always that characteristic Burgess swagger, that conscious display of virtuosity, and nagging sense of prevailing evil: "I believe the wrong God is temporarily ruling the world and that the true God has gone under."

Burgess left critical opinion sharply divided. His admirers included Gore Vidal, A S Byatt and William Boyd, while Kingsley Amis, Christopher Ricks and Geoffrey Grigson were among the detractors. The Times obituarist acclaimed him "a giant", while the poet Kathleen Raine dismissed him as a "journalist".

Burgess died 12 years ago, and now two biographers have targeted him across the same firing-line. On the heels of Roger Lewis's blisteringly hostile caricature in 2003 comes Andrew Biswell's pointedly-titled The Real Life of Anthony Burgess. Lewis damned Burgess's fake persona; Biswell is more respectful and meticulous in marshalling the detail to reveal both the public figure and the demons driving him. When Burgess gets things wrong, Lewis derides his "demented fantasising"; Biswell prefers to attribute such failings to "false memory" or a harmless Irish tendency to favour "the Big Story".

How far has Biswell managed to penetrate the mask of spirited geniality and scholarly posturing? He has certainly lifted the curtain sufficiently to reveal a darker self lurking in the wings: a man gripped by frustrations, an all-consuming guilt and a ruthless determination to turn himself into a literary figure of note. He also shows how real life and fiction were often intertwined, and how his best comic creation, the down-at-heel F X Enderby, is little more than "a mirror image" of an earlier moth-eaten Burgess.

John Anthony Burgess Wilson was born in Manchester in 1917 to a cinema pianist of Irish descent and a music-hall artiste who died in the post-Great War flu epidemic. Educated by Jesuits, he read English at Manchester University where he was already portraying himself as Joyce's artist as a young man. After war service with the Education Corps, he became a schoolteacher, then a British Council lecturer in Malaya where, as John Wilson, he wrote four novels. However, the strain of heavy drinking and a turbulent marriage led to a breakdown. Diagnosed with a brain tumour and given just a year to live, he was repatriated in 1959 and began writing furiously (as Anthony Burgess), hoping to leave a decent legacy to his widow.

However, it was his wife Lynne (a disturbed and suicidal alcoholic), who died first, in 1967, of cirrhosis, testimony to almost 30 years of excess. The marriage had become a folie à deux, from which a frenzied creativity was Burgess's principal means of escape. In fact, says Biswell, without Lynne there would have been no Anthony Burgess, for whom the Sturm und Drang of his marriage became grist to his fiction-mill.

He was soon remarried - this time to an Italian countess with whom, mysteriously, he had earlier produced a son. In 1968, the couple chose exile, first in Malta, then Italy and finally Monaco. Burgess died of lung cancer in London in 1993 and was buried in Monaco - exiled even in death.

From this tumultuous chronicle two delightfully comic images emerge: one of Burgess repelling a gang of Manhattan muggers with a swordstick, the other of the stony-faced, gravel-voiced William S Burroughs reading Jane Austen to a bed-ridden Lynne Burgess in Tangier.

There is a rattling good story to be told, and Biswell makes a very good fist of it, although finally the avalanche of Burgess's later work overwhelms the narrative. Clearly a subject so protean, loquacious and self-contradictory requires a biographer prepared to stand back and regard him with a detached if quizzical eye. Biswell succeeds admirably, adopting just the right posture throughout.

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