At the end of a phone line in Spain, Alan Warner is having a domestic problem. ‘Excuse me a minute,’ he says when I ring. ‘I’ve just got to rescue a cat.’ There is a long pause punctuated by some muffled scuffling and mewing. ‘Sorry about that. It’s one of the strays we took in. You know we used to even have a three-legged cat called Landmine.’ Somehow, these acts of feline charity seem appropriate. At 43, Warner, one of the finest writers of his generation, has always had a sympathy for waifs and strays in his fiction. Morvern Callar, the eponymous heroine of his astonishing debut (played beautifully by Samantha Morton in the Lynne Ramsay movie), floats through the novel in an emotional vacuum after her boyfriend kills himself. The apocalyptic landscapes of These Demented Lands and The Man Who Walks are peopled with loners and misfits. Even in The Sopranos – his cheeriest book to date – the irrepressible convent girls scratch and spit like fighting tabbies.

No surprise, then, that the protagonist of Warner’s most recent novel, The Worms Can Carry Me to Heaven, finds himself in the grip of an existential crisis. Manolo ‘Lolo’ Follana, a fortysomething playboy from a small coastal town in Spain is told he is suffering from a life-threatening sexually-transmitted disease. Instead of being driven to despair, however, this news inspires him to Proustian reverie about past erotic adventures and his childhood.

It’s been a couple of years since Warner and his half-Irish, half-Spanish wife, Hollie, swapped Dublin for Spain, settling in Javea on the Costa Brava, the same town his central character decamps to at the end of Morvern Callar. But it’s clear that the landscape has taken a grip of his imagination. Just as his debut novel grabbed the area around Oban and refracted it through a dream-like mirror, Worms adds a fantastic veneer to the azure sea, Moorish holiday villas and scrub land of the Spanish coast.

Follana lives in the Phases development, blasted from the pink rocks and occasionally cut off by the rising tide. This alien terrain could have come from a Ray Bradbury science-fiction story: ‘The rigid cuboids and geometries of the new apartments around me – some with large satellite dishes pointed at the moon and occupying their entire balcony so that nobody can sunbathe there – are like a honeycomb of monks’ cells in a modern seminary with private spiritual exercises being conducted within.’ Even the names of the railway stations are hauntingly futuristic: Kilometre 4, Disco. ‘I read JG Ballard, in the intro to Vermilion Sands I think it was, where he describes the whole coast from Portofino to the south of Spain as a 1000-mile linear city that only goes inland 300 yards or so,’ Warner explains. ‘That image has grown for me; it literally becomes more concrete.’

When Warner began writing the book, he was petrified people might think he saw himself as an expert on Spanish culture: ‘I didn’t want to be some kind of anthropologist.’ He needn’t have worried. Follana’s world has a feel all of its own, which is matched by his unique narrative voice. When Worms came out, a particularly pedantic critic dismissed the book, complaining that it was peppered with grammatical inaccuracies. What they failed to see was that the narrative reads as though it’s been translated near perfectly from a foreign language, but with the occasional lapse of idiom, the odd word that’s not exactly wrong but somehow doesn’t feel right.

The entirely deliberate effect of this can be comic or jarring. ‘The whole novel is some kind of distancing technique,’ Warner says. ‘It’s a novel about language and the inadequacies of language, in the same sense that Morvern Callar is a novel about language.’ At the heart of the book is a contrast between the lucidity of Follana’s narration and the emptiness of his life. One critic memorably described him as ‘wearing his disconcerting vulnerability on his sleeve like a designer watch.’

‘Follana is in a sense totally without purpose, almost an irrelevancy in the design company he’s created,’ Warner says. ‘To him life is strangely meaningless.’ The possibility of redemption comes in the form of Ahmed Omar, a Somali illegal immigrant who has made the dangerous journey by boat from Africa to Europe. Like Follana, Omar has ‘The Condition’, and soon the Somali becomes a confessor figure for the vain Spaniard.

Warner can be a heartlessly funny writer when he chooses. But the section of the novel in which he charts the unlikely relationship between these two men is not just funny but emotionally compelling. Some readers may find it hard to see beyond Lolo’s narcissism. For Warner, though, Follana is ‘definitely one of the good guys.’ Does he identify with the character? ‘I’ve never felt like somebody who writes about his own life. I’m not like Follana in so many ways but I’m certainly sympathetic towards him.’

So no mid-life crisis, then, but there certainly seems to be a new maturity to Warner’s writing in The Worms Carry Can Me to Heaven and he has often mentioned how he took early inspiration from Andre Gide and Albert Camus. Two of the first novels he ever bought, aged 15, from the Oban branch of John Menzies, were The Immoralist and The Outsider because he thought they might be racy. But never before have those continental influences been so obvious in his writing. The limpid prose of Worms is as refreshing as a glass of cold water on a hot Spanish afternoon. It has a similar energy to These Demented Lands and The Man Who Walks, but fewer self-indulgent excesses. ‘This book is less hysterical and out of control than they’ve sometimes been in the past,’ Warner agrees, although he seems to feel ambivalent about this fact, adding that waywardness and hysteria are good qualities in a novel.

Yet it’s not just the polished style that makes Worms remarkable. The ambition of the story is dazzling. Pared down to just under 400 pages from the manuscript’s original 800, this is a novel of huge, universal themes: from loneliness and mortality, to materialism and the plight of illegal immigrants. As Warner is at pains to point out, Omar is more than just a convenient catalyst for the plot. ‘His situation isn’t fiction. It’s hardcore fact. I’ve met people like him. What can be more justified than breaking into a country to save your own life?’
Warner is probably right when he says that ‘some people who liked Morvern Callar might not like The Worms Can Carry Me to Heaven. They might find it boring.’ More than most Scottish writers of his generation, he has been pigeonholed. When Morvern Callar was published in 1995, it was almost inevitable that the media would bracket him with Kevin Williamson, Irvine Welsh and the so-called ‘chemical generation’ of writers. ‘The press were determined we would all be in one big gang,’ he recalls. After all, his debut mentioned sex and pop music, and some of his earliest writing had been published by Williamson’s magazine Rebel Inc. Warner’s subsequent appearance in Sarah Champion’s Disco Biscuits – an anthology of stories based around nightclubs and the ecstasy scene – helped cement the image.

Then there was the fact that he came from a village near Oban and used to work on the railways. The caricature of Warner as some kind of noble Highland savage who against all odds had somehow learned to read and write was a powerful one, especially since it allowed comparisons to be made between the author and his character Morvern. It was true that he grew up in a household with no books, the son of a heavy-drinking ex-army sergeant. But it was almost as if London literary editors – who could no more find Oban on a map than Bora Bora – expected him to step off the Euston train wild-eyed and shoe-less.
‘It was always “former railway worker”, never “former teacher of failed GCSEs”.’ To be fair, he has often played up to the hedonist of Scottish letters image, embarking on mammoth drinking sprees with interviewers. He told one New York journalist how he had got so drunk that he ran into the men’s loo at a pub and threw up over a man who happened to be sitting on the toilet. Fearing he might get beaten up, he got his revenge in first by hitting the poor man in the face and running away. Another journalist was regaled with the story of how he preferred taking ecstasy at Edinburgh Zoo to clubbing: ‘cheaper admission, prettier girls, colourful parrots.’

He parties a little less now. ‘But the biography is already forged,’ he says. ‘It’s hard to escape it. I’ve noticed that a lot of my reviews, especially in Scotland, still tend to review me and my career rather than my books.’ A persistent side effect of this is that it’s easy to underestimate how nuanced and carefully crafted the best of his work is. Happily there’s not long to wait for the next book as Warner is currently writing a sequel to The Sopranos. ‘I don’t want to give too much away except to say that quite a lot of time has moved on and there’s a change of geographical location.’

Meanwhile, with his business partner Sophy Dale, Warner is putting both money and time into the Long Lunch Press, a small publishing venture that prints the work of upcoming literary talents alongside that of established writers such as Don Paterson, James Meek, Ali Smith and Annie Proulx. The enfant terrible has made a seemingly seamless transition to benefactor and supporter of new talent. But are there no Lolo-style regrets? ‘I don’t think I’ve had my mid-life crisis,’ he jokes. ‘But I’m looking forward to it with glee.’

Alan Warner, The List Event, 17 Aug, 8.30pm, £8 (£6); Janice Galloway & Alan Warner, 18 Aug, noon, £7 (£5); Both events at Charlotte Square Gardens, 0845 373 5888.