Porno by Irvine Welsh

Glasgow novelist Louise Welsh salutes her Edinburgh namesake's satire of new money and old professions

"This is a badly written celebration of yob culture": Spud Murphy's history of Leith, "aboot skag n'Aids n' that, aboot the boys that wir wiped oot, the pure bums and the decent cats", is rejected in establishment English by a Scottish publisher. The divide between the language employed to dismiss Spud and his compadres, and the language used by them, undercuts Porno.

Irvine Welsh has returned to the cast of his first novel Trainspotting in a friends-reunited sequel which knocks on the head any notion that post-parliament Scottish writers are going to be reduced to novels about adultery, university intrigues and calorific contents. The boys are back in town. But the town has changed.

Some children's names are down for Saughton jail as sure as others are down for Gordonstoun. It's no surprise to meet Francis Begbie straight from the big concrete hotel, porridge complexion and outmoded clothes. Begbie is empowered and limited by the violence he personifies. Leith slang christens him both Generalissimo and Beggar. He notices the change in his home town immediately: "Ah strides up the Walk, scanning the coupons on the passer-by, trying to find some ... I recognise ... Whaires all the real gadges now?" Where indeed?

Take a walk by Scotland's Parliament and you'll see transformed streets: media offices, smart bars and restaurants, luxury apartments. Raise your eyes to the horizon and you'll see council high-rises. They have changed, too, their exterior refaced to make them more aesthetically pleasing to new gadges. Not much has been done to their interior. After all, no one of import is going to view them.

In central Edinburgh, council scheme tenants worry about their future. As Spud says, "'its aw changing man. Yuv goat the Scottish Office at one end and yuv goat the new Parliament at the other ... Ten years time there'll be nae gadges like me n' you left ... They only want cats wi cash in toon".

With change, though, comes opportunity. Simon "Sick Boy" Williamson has acquired his auntie's bar, Port Sunshine. He reckons he's got the attitude and lack of morals to make it work. He'll get rid of "those people who have no place in the new Leith ... load of dirty auld mingers". What Sick Boy forgets is that he's a product of Old Leith, and there's more than a touch of the minger about him. As evidenced by his decision to build on his experience as a minor pimp and become a fully-qualified flesh bandit.

Irvine Welsh sticks two fingers up at the tartan escort brigade. Nikki Fuller-Smith (of whom more later) experiences a humiliating encounter with a lecturer in Scottish Studies, who has just attended a meeting of the Caledonian Society, and a member of the Scottish Parliament, Rory McMaster (there's the occasional use of the sledgehammer about Welsh's iconography). Welsh is no self-conscious Scot, but he does draw on Scottish literary tradition. Like writers as diverse as Walter Scott and James Kelman, he employs the vernacular to give voice to the man in the street. His ear for the rhythm and rich vocabulary of Edinburgh speech is unsurpassed. Welsh is a prime satirist and, like the best satirists, he gives society a reflection of itself. He successfully places the Scottish landscape in a wider political and geographic context.

Where Porno does irritate is in the person of Nikki Fuller-Smith (Fuller-Shit, as she is nicknamed in the book). Edinburgh relishes its reputation for duality. Deacon Brodie – gentleman by day, "thiefy boy" by night – is a city icon. The town has a tradition of tolerated prostitution and adult entertainment. Robert Louis Stevenson writes fondly of the city's "hoors", and before lap dancing, Edinburgh had go-go.

Porn is an ideal subject for Welsh. But why has he chosen to view it through the confused gaze of Nikki F-S? She's a wet-dream fantasy; body-dismorphic bulimic. An English girl with a daddy complex and an allowance, she describes being a poor student as "a racket". Nikki disturbs the balance of the book, hinting at a colonial corruption absent from the rest of the novel. Diane, Renton's sweetheart, is by contrast idealised. No girl wants to be put on a pedestal. It's too far to fall.

Sick Boy recruits Renton, who's been hiding out on the Amsterdam club scene, to help with porn production and distribution. Renton is the best adjusted to the modern world, a confirmed capitalist, the only one of the Trainspotting crew doing well. He's the last person Simon should trust.

Like all good tales, the ending is in the beginning – but I defy you to see it coming. Porno builds to a page-turning climax and a final image of dreadful hope, which embodies Leith's motto: "PERSEVERE".

Louise Welsh's novel 'The Cutting Room' is published by Canongate