Instead, he distinguished himself as a writer of literary historical adventure novels in the early 1980s, before the genre became fashionable. That made him a black sheep in literary London - not that Ackroyd, a workaholic who lives in happy isolation, ever complains.

He has earned more acclaim as a biographer, publishing works on Thomas More, Ezra Pound, Dickens, Shakespeare, Chaucer and Eliot, and netting eye-popping advances. Last year he was paid #3 million to write, in 12 years, a six-volume history of England.

Ackroyd will have you believe he already has forgotten his new novel, The Casebook of Victor Frankenstein. 'As soon as I've started work on another book, then the previous one evaporates,' he says in his plummy, lisping voice. 'I can never remember what happened.'

Ackroyd relocates the events of Mary Shelley's classic novel from 19th-century Oxford to London as Dr Frankenstein recruits grave-robbers to supply corpses for his experiments. Ackroyd had no high-minded rationale for retelling Shelley's tale, but 'just fit her plot in an entirely different context and used it for the hell of it'. The idea germinated when he re-read Frankenstein for a BBC television series on the Romantic period he was presenting.

The corpulent Ackroyd is an unlikely television personality, resembling, in his own description, a cross between Alfred Hitchcock and Margaret Rutherford. 'I hate watching myself. I turn it off or I regret it. I don't like the way I look.'

Ackroyd brings Frankenstein into contact with a cast of Romantics including William Wordsworth, Samuel Coleridge, Lord Byron, Percy Shelley and his novelist wife, Mary. 'It's often said Edgar Allan Poe was the progenitor of science fiction, but I think Mary Shelley deserves that accolade more,' Ackroyd says.

Fiction requires less invention than biographies for Ackroyd. 'In fiction, you have to remain true to the original inspiration, whereas in biography there are techniques you can use to hide your lack of information. You can gloss over a couple of years in a sentence. You can not dwell upon certain subjects,' he says.

If his research is exhaustive - he read 100 books on Shakespeare before beginning his 2005 biography of the Bard - that's not surprising when he talks about writing as a form of theft. 'When you write, you just re-order old books. Chaucer had the same theory. He often just took large passages from other people's books and rewrote them.'

Ackroyd was born in 1949; shortly after, his father Graham abandoned the family. Ackroyd has no idea why he left - he and his mother Audrey never discussed it. Nor is Ackroyd's sexuality a topic he and Audrey, a staunch Catholic, ever broached. He visits his mother about every three weeks and they discuss 'just trivial, ordinary things like the weather ... Serious talk just bores me. I reserve seriousness for the writing,' he says.

Graham Ackroyd tried to make contact with Peter as an adult, but his son didn't want to meet him. 'It was too late in the day,' Ackroyd says. 'I'd formed my own character.' Did he feel anguish as a child knowing his father deserted him? 'No,' he says, sounding bemused. 'Not at all.'

It may seem odd that a student of lives has so little interest in his own family, but Ackroyd says he shares similarities with his subjects. 'In that sense, my biographical subjects are very much like me,' he says. 'Blake renounced his family; Dickens disliked most of his family; More abandoned his family; Shakespeare never paid any attention to his family.'

One can speculate about how growing up on a London council estate contributed to his ambition and obsessive work ethic, but Ackroyd will have none of that. 'I don't think that had a great effect upon me,' he says.

Still, on heading to Cambridge University, the would-be writer was determined to shed his cockney vowels. 'I had a feeling I might be taken more seriously. As it turned out, cockney accents were all the rage in the late 60s and 70s so I was quite wrong.'

There followed a master's degree at Yale, where he wrote the dissertation on modernism that became his first book, Notes for a New Culture (1976). On returning to London, Ackroyd, aged only 23, was named literary editor of The Spectator. As a young child he wanted to be a tap dancer but by adolescence had settled on becoming a poet. He published four collections of poems but abandoned verse after writing his first novel, The Great Fire of London (1982). Not that he makes any grand claims for the novel form. 'I wouldn't say I've been educated at all from fiction. I just treat it as an amusement.'

At Yale, Ackroyd met his partner of more than two decades, Brian Kuhn, a dancer and model who died of Aids in 1994. Kuhn's illness eradicated Ackroyd's fear of death. 'He was perfectly accepting of it,' Ackroyd says. 'He never complained, never moaned. Just before he died he was singing in the bath.'

Ackroyd has had one partner since Kuhn's death, but says he no longer desires companionship. Yet lest he be misunderstood, Ackroyd insists he has never needed love. He and Kuhn didn't have sex for nearly the last 15 years of his life. Of sexual desires, he says: 'I don't have those any more - none at all.'

It was Kuhn - and anti-depressants - that Ackroyd credits with seeing him through a six-month spell of 'nervous depression' in 1988. He was struggling with his first biography, T.S. Eliot: A Life, and his novel, Chatterton, had just missed out on the Booker Prize. 'I suppose I was stressed because I was tired,' he says.

His body cracked up again in 1999 when he suffered a major heart attack on the day he finished his monumental work, London: The Biography (2000). 'I suppose I was holding off until I could write the end,' he says. Ackroyd spent a week in a coma but 'strangely enough' the near-death experience had no impact on him.

The attack was probably caused by his excessive drinking and smoking, but it didn't motivate Ackroyd to change his habits. 'I opened a bottle of wine on the ward after the operation!'

Reports that he often falls over from drunkenness at parties are, he says, 'completely exaggerated - I haven't been to a party in years'. Is it true, though, that he once sat in the front row at a play about Lucien Freud and heckled the actors so rudely one of them butted his companion after the performance? He giggles, seeming to enjoy the gossip. 'That is true, yeah. Hehehe. I'd drunk too much that day.'

And reminded of the night he spent in prison having been intoxicated at an awards ceremony, Ackroyd sighs. 'It was a night of very heavy snow and I was zigzagging my way home. They were frightened I was going to fall asleep and die in the snow, so they took me into the care of their cells.'

He calls himself 'bibulous' rather than 'alcoholic', explaining: 'I've abstained for periods of months on end and I don't drink during the day.' Ackroyd starts drinking after his hour-long evening walk through the capital. He admits to having little interest in London's cultural life but feels a profound sense of identity with the city.

'I think of myself in terms of the great predecessors of what I call the London tradition - cockney visionaries such as William Blake, Turner, Dickens, Chaucer. It means a sensibility which is theatrical, heterogeneous and a humour which is broadly pantomimic.'

As well as the six-volume history, Ackroyd is now working on his 15th novel, two translations and a biography of novelist Wilkie Collins. Perhaps his lack of introspection explains his productivity. As he says, 'If I was forever investigating my own methods and beliefs and attitudes, I probably wouldn't get around to writing much at all.'

Writer's notes

Name: Peter Ackroyd

Age: 59

Family: single

Lives: London

Genres: literary fiction; biography; poetry; criticism

Latest book: The Casebook of Victor Frankenstein (Chatto & Windus)

Current projects: a six-volume history of England; another novel, Three Brothers; translations of Thomas Malory's The Death of Arthur and Geoffrey Chaucer's The Canterbury Tales; a biography of Wilkie Collins

Other novels: The Great Fire of London (1982), The Last Testament of Oscar Wilde (1983), Hawksmoor (1985), Chatterton (1987), First Light (1989), English Music (1992), The House of Doctor Dee (1993), Dan Leno and the Limehouse Golem (1994), Milton in America (1996), The Plato Papers (1999), The Clerkenwell Tales (2003), The Lambs of London (2004), The Fall of Troy (2006)

Non-fiction: Notes for a New Culture: An Essay on Modernism (1976), Dressing Up: Transvestism and Drag (1979), T.S. Eliot: A Life (1984), Dickens' London: An Imaginative Vision (1987), The Life of Thomas More (1988), Ezra Pound and His World (1989), Dickens (1990), An Introduction to Dickens (1991), Blake (1996), London: The Biography (2000), Albion: The Origins of the English Imagination (2002), Chaucer (2005), Shakespeare: The Biography (2005), Turner (2006), Newton (2007), Thames (2007), Poe: A Life Cut Short (2008)

Children's non-fiction: The Beginning (2003), Escape From Earth (2004), Kingdom of the Dead (2004), Cities of Blood (2004), Ancient Greece (2005), Ancient Rome (2005)

Poetry: Ouch (1971); London Lickpenny (1973); Country Life (1978); The Diversions of Purley (1987).

Other jobs: literary editor of The Spectator; The Times chief book critic; TV presenter

What the critics say: 'At the start of his novel-writing life, Ackroyd made postmodern, London-based historical novels seem at once daring and fun; they gained him his reputation, and had a considerable influence. But, like Victor Frankenstein, he is now being overwhelmed by the thing he made.' - The Guardian on The Casebook of Victor Frankenstein