FICTION:Irvine Welsh's prequel to 'Trainspotting' is an uneasy hybrid, but it has a firmer grasp of the social forces that keep the gang at the bottom of the food chain

Skagboys By Irvine Welsh Jonathan Cape, 548pp. £12.99

THIS READER FIRST heard of Irvine Welsh’s debut novel, Trainspotting, not from a book reviewer or college professor but from a sound engineer at Lansdowne Studios in 1994. “This,” he said, “is the only book telling the truth about what’s happening now.”

Trust a man who listens for a living. Trainspotting was an example of a mysterious chemical reaction that occurs when subject and style fuse, generating a synoptic kaboom. Like any great first-person vernacular yarn – The Adventures of Huckleberry Finn, Riddley Walker, True History of the Kelly Gang – it had its own dialect, and Welsh’s Scottish patois forced the reader to slow down and parse that narrative voice, to attune to the rhythm of the words and chew over each paragraph. The experience was akin to decoding the hissing sounds of some obscure blues recording. But once you were in you were in, and many of us were loath to leave that world, grimy though it was.

The book became a pop-culture phenomenon, and Welsh, along with the rest of the Children of Albion Rovers fraternity, found himself at the vanguard of one of the most significant literary movements of that decade, inheritors of a street-savvy avant-garde tradition passed down from Alasdair Gray and James Kelman, with a dose of beat energy and rap-artist gutter chic thrown in for good luck. Welsh followed it with a succession of ever more outre tales (The Acid House, Marabou Stork Nightmares, Ecstasy, Filth) that put him alongside “transgressive” brutalists such as Bret Easton Ellis and Chuck Palahniuk. (We’ll draw the line at Dennis Cooper.)

But as the years went by he seemed afflicted with the curse of Kerouac. The highly stylised energy of his debut brought fame and money, but if he stayed on the same course he seemed doomed to repeat himself. And yet what writer, having spent years forging such a distinctive voice, could summon the will to abandon it?

Welsh confronted this problem with Porno (2002), a sequel to Trainspotting that wobbled unevenly between Leithspeak and orthodox narrative. Since then he has continued to churn them out, an increasingly peripheral, if prolific, figure. This writer saw him read at Electric Picnic a couple of years ago, and it was a strangely deflated affair.

Now comes Skagboys, a hefty, 548-page prequel to Trainspotting, set in 1984, a time of mass unemployment, heroin epidemics and Aids scares. From the opening set piece, a diary account of a miners-versus-police skirmish written in Mark Renton’s scrawl, it’s clear that Welsh has not so much staged a return to form (the book is culled from the original word horde that yielded the Trainspotting material) as taught himself to sing again by listening to the voice of his younger self.

If Trainspotting was a collage of urban myths and shaggy drug stories that, stitched together, formed a panorama of the Naked City via Naked Lunch, Skagboys unfolds at a statelier pace. It’s quite the hybrid: the tempo suggests beloved English “institutions”, such as Austen or Dickens; the dialogue evokes Ol’ Dirty Bastard if he’d been born in the Scottish projects. Skagboys might lack the ruthless compression of Trainspotting, but it has a firmer grasp of the social forces that keep Renton, Sick Boy, Begbie, Spud and pals at the bottom of the food chain. Thumbnail accounts of Tory policies and Thatcherite blight, of part-time work replacing jobs for life, of bogus schemes designed to take the long-term unemployed off the live register (juking the stats, in Wire-speak), give the book a formidable social conscience that offsets the amoral antics of the cast.

But Welsh can be maddeningly sloppy. Bits of modern jargon contaminate the period prose (as far as I can recall, phrases such as “failure is not an option” were not part of the national conversation in 1984). The author has a superb ear for dialogue, but when he flits from first-person Leith to third-person Queen’s English, his prose sounds defanged, padded with adverbs, almost prissy.

Compare the following two passages:

Janey grows animated as she leaves her cell and walks down the corridor in a line of women, led by a solitary uniformed one, who opens a series of locked doors . . . After a few minutes, the visitors start to file in, and there’s Maria, walking towards her, acknowledging her with a strained smile.

“Thing is, ah’m jist wantin sorted oot up here cause ah’m feelin bad, bad, bad, man. Ken? Ye sortay wonder if the cats’ll gie ye morphine fir a burst airm. If no, ah’m pure hightailin it doon tae Johnny Swan’s, wi aw these rings, neckies n bracelets in ma poakit.”

Hard to fathom why the author doesn’t commit himself to the electric style of the latter all the way through. Parts of the story might demand an objective voice, but why shouldn’t an omniscient narrator have an accent?

Despite such nit-pickings, Skagboys is a compelling tale. Welsh’s characters meander through ever-decreasing circles of heists, scores, cold turkeys and grubby sexual encounters, following no discernible narrative arc, yet the book only occasionally loses propulsion. A scene in which Begbie shows mercy on a surrogate uncle, then relents and batters him anyway, functions both as a comedic skit and a chilling portrait of a headcase – albeit the kind of headcase who can break your heart with a Rod Stewart song.

Skagboys is at once a regression and a return to former glories. If it were a debut novel, it might well be hailed as a cult classic. As it stands, it’s uneven and overlong but still a seriously entertaining piece of work.

Peter Murphy is the author of John the Revelator (Faber). His second novel, Shall We Gather at the River, is due to be published next February