It was, apparently, an accident. He did not intend to destroy Irving's moment of glory, though he's bullish about his skill. "Frankly, I'm rather a good skater - TV crews often film me," says Irwin, in all other respects a model of modesty. "Roller-blading keeps me sane and saves me physically." He often Roller-blades in London parks, keeping a pencil in his pocket to write as he twirls.
Irwin is not only a survivor of the tumultuous Sixties; he can even remember the decade. He shouldn't be able to, of course: he should be a shambling wreck, his mind and body reduced to tatters. But there's no justice in this world. Here is one of the best minds of that generation and, far from having dashed itself to pieces between the ghastly Scylla and Charybdis of drugs and booze, it is still functioning as brightly as ever.
Irwin is one of our leading Arabic scholars, and the author of five well- reviewed novels, with another out next week (Satan Wants Me, Dedalus, pounds 14.99). The two worlds do overlap: his first work of fiction, The Arabian Nightmare, had an archetypal success story. It was published by a small press in 1983, and sales were sagging until Christie's found themselves with a clutch of medieval Arabic manuscripts to be auctioned.
No one there knew what they were about. Irwin is one of the few people in the country, probably in the world, who can pick up a medieval Arabic document and read it like today's Sun. Sometimes, indeed, it may turn out to have a strange similarity, containing perhaps an account of the "crocodile position" assumed by patrons in the brothels of Cairo or a treatise on the concept of "magnetic meat".
On this occasion, the staff of Christie's sent out for his learned works, and into the bargain got a copy of The Arabian Nightmare. One of them liked it so much that she sent it to a friend in Germany, who translated it and recommended it for publication. So successful was it there that Viking took it up and published the English text again.
This engrossing and totally original tale of metamorphoses and night fears, set in medieval Cairo, has since become a runaway success. It's worthy of The Arabian Nights, on which Irwin has published a commentary, and which he studies with a special viewpoint. "How do these Arab storytellers work? What are the creative mechanisms? I'm looking at it partly as an academic, but also as somebody who does it himself."
Irwin gave up academia to become a house-husband and to write fiction. He was then absorbed with household duties and the care of their small daughter while his wife resumed her career as a high-ranking official of Parliament. He knew that he wanted to write, but was not certain that he would in fact pursue either his scholarly work or that of the novelist.
That was 20 years ago, and he has now carved out an interlinked career in both departments, fiction and Arabic studies. The novels have been varied in settings and subjects, but certain themes run through them all. "All my novels are about madness of one kind or another - obsession, delusion, drunkenness." The Limits of Vision was born out of domestic claustrophobia: a housewife obsessed with dust finds herself conversing with great minds of the past, such as Leonardo and Darwin, in an imaginative investigation of suburban psychopathology. Prayer-Cushions of the Flesh returned to the medieval Middle East, with an erotically-charged Topkapi harem and its sexual delusions. Like Irwin's other novels, it has a suggestion of the conjuror's performance, of fiction as a series of secret worlds opening one into another.
In Satan Wants Me, about a Sixties hippy who falls in with the occult, Irwin quotes Aleister Crowley: "magic is a disease of language." "Crowley was an intelligent man," he comments. "Magic and language are intensely bound up with each other; it's a running theme in my novel."
But he would not call himself a magical realist. "I can see why I might get reviews where I'm called that - my books are realistic but they've got a lot of magic in them, things happen which are not of the logical world. On the other hand, I actually hate magical realism; I can't stand those novels where anything goes: a house walks about on chicken legs or a woman has four hundred babies." He is more interested in the discipline of telling the story.
The idea for Satan Wants Me came quite recently, on a visit to a museum of conjuring, a place full of old occult paraphernalia in the Marais district of Paris. But the interest in Crowley started a long time ago.
He bought a copy of the master's Magic in Theory and Practice in Oxford in 1965. "I thought I might use it for spells and didn't know I would ever use it in a novel. Trouble is, if you want a spell to achieve spectacular results, you have to do things like getting the skin of a gazelle taken from its mother when it's eight months old, and steeped in turmeric and ground-up lapis lazuli."
There's not much fear of Irwin performing Satanic rituals in darkest SE11. In any case, Peter, the narrator of Satan Wants Me, has a constant intelligent viewpoint on the diabolic caperings that both attract and repel him. Even as he seduces a sacrificial virgin for his dark master, he is fully aware that he is actually plotting the sexual enslavement of a perfectly nice hairdresser called Maud.
Fortunately Maud, though not exactly a brainbox, is no wimp. She is a karate expert, among other attributes, and Irwin says he identifies with her more than with the colder observing brain of the central character. "Peter is cleverer than the people he's dealing with. There's always a bit of his brain that's not castrated. But I identify more with Maud. I don't want to write about clever people standing round talking."
There's also something of Irwin embodied in the writing demon, Pyewhacket, who inhabits Peter from time to time. "It's the thing that makes me do what I don't want - that pops up in the head and out of the mouth. But it does represent the way writing goes when it's going well, a silent voice that comes from nowhere, almost dictation."
If this sounds shamanistic, the book nevertheless has a solid grounding in Sixties reality. It also has plenty of humour. The diabolism is enacted in cosy Swiss Cottage, and the book is full of pragmatic details such as the sudden alarming appearance of a garden gnome on a doorstep. "Mr Cosmic believed that the plaster figures of gnomes, though degraded in their present-day functions, could still serve as the foci for the chthonic powers of the earth."
The Sixties background comes not only from the writer's memory. Irwin researched it properly by looking at documentaries and magazines, and was struck by how much in that fabled decade was actually very ordinary. The mundane presences of Typhoo and Brylcreem and Woodbines continued in an unchanged world, although the razzle-dazzle of fashion and pop dominates our recollections.
Drugs, of course, had a high profile in youth culture. There are some bad trips in the book, out-of-the-body experiences that are very unpleasant indeed. "LSD was still legal when I did it," remembers Irwin. "I think there's a kind of inbuilt mechanism in it. The longer one goes on, the nastier the trips get. It's downright anti-addictive."
So the author is clearly not a slave to the addictions of the Black Arts, nor to any others. When I interviewed him, however, I must confess that it had gone through my head for a moment that his home might be the house of a magician. It's built of soft red brick, set exactly where one would not expect to find a house at all, tucked between a pub and a school. It has a secretive high-walled garden; the interior has soft green walls and Indian cushions spread around. But the huge private library is in apple-pie order, and I found the communer with Pyewhacket absorbed over The Times Literary Supplement, for which he is a consulting editor.
Irwin has a long scholarly bibliography to his credit and is currently working on a book about Orientalism. His anthology of Arabic literature is due in the autumn. It's a fearsome rate of productivity which only strict discipline can achieve. Any explorer of the irrational must have remained within the bounds of sanity to achieve it. Way out, man... but not too far.
Robert Irwin, A Biography
Robert Irwin was born in 1946. He was educated at Epsom College and won a major scholarship to Oxford. After a lectureship at St Andrews he became a house-husband and writer, and has continued to produce both fiction and academic work. He is a widely acknowledged expert on The Arabian Nights. His first novel was the celebrated cult book, The Arabian Nightmare (1983), followed by The Limits of Vision (1986), The Mysteries of Algiers (1988), Exquisite Corpse (1995) and Prayer-Cushions of the Flesh (1997). His latest book, Satan Wants Me, a novel of the occult set in Sixties Britain, is published next week by Dedalus. His non-fiction includes The Arabian Nights: A Companion (1994) and Islamic Art (1997); his anthology of classical Arabic literature will be published by Penguin in the autumn. He lives in London with his wife and daughter.