IAIN BANKS IS, he admits, a 'funny mix': a best-selling author undoubtedly; an obsessive certainly. He nods vigorously, twice. A schizophrenic, perhaps?
'Come on,' he says crossly from behind his refuge of beard, glasses and swatch of tabletop. 'I don't hear voices in my head or anything.'
But his is undeniably a split personality - a trait that permeates all that he does, not least his work. He writes mainstream novels as Iain Banks and equally popular science fiction under the pseudonym Iain M Banks.
Even his 'regular' titles are split down the middle. 'I write nice and nasty books,' he says, slightly smugly.
Banks is an amalgam of contradiction. A real-ale loving, computer game geek with a very unstuffy passion for fast cars, drugs, sex and violence; a self-professed feminist who admits to cheating on his wife with a string of affairs before their marriage.
He confesses: 'You do become more attractive as a man when you become more successful. It's hard not to take advantage of that.'
Ostensibly open but in reality guarded, he hides behind a bluff of bonhomie and laughter. He is gregarious but, one suspects, always just one step removed - a classic only child. 'I always had friends,' he says. 'But I never shared my life that intimately with children when I was a kid. I'm deeply egocentric.'