HE'S always been on the radical side, a "shock horror" voice that rails against middle-of-the-road convention with a literary style known for drawing back the veil on genteel Edinburgh, exposing its rancid, drug-fuelled underbelly.
• Irvine Welsh
Author Irvine Welsh comes stamped with the warning that, at some stage, he's going to blurt out something that makes you stop, stare wide-eyed for a moment and wonder if you heard right.
But it's true. Welsh, the man who made Trainspotting a global phenomenon, is now into a different kind of transport.
For Trainspotting, read tram- spotting.
"I can see the headlines in the Evening News," he laughs, "Irvine Welsh loves trams!
"I must be the only person in Edinburgh who actually does love the trams. But I think it's a great idea. Okay, they've made a complete a**e of it, but if Edinburgh wants to be a modern European city, it needs trams."
Of course, the fact that the enfant terrible of Scottish literature - who's done more to highlight Edinburgh's blemishes than most - has now thrown his support behind the beleaguered trams project is bound to be a headline in waiting. Particularly as he's here in Leith, where he was born, the part of town that's arguably suffered the brunt of the trams fall-out.
But he's not made this flying visit home from his Chicago base simply to offer his opinion on modern urban transportation. Instead, he's sitting in the cafe of a Leith drill hall, now Out of the Blue, where he hasn't ventured since his Boys' Brigade days, surrounded by starry-eyed young thespians desperate to be introduced to their literary hero.
"I had a Trainspotting poster on my wall for years. It's amazing that he's here to give us his backing," says Duncan Kidd, 27, from Newington, one of a group of writers and actors from Leith-based Strange Town theatre company, which has just received the stamp of approval from surely the highest profile supporter they could have ever hoped for. For Welsh to lend his support to the company's first foray into appearing at the Fringe, it's a no-brainer.
Strange Town - a theatre company for young people aged from just eight to 25, who not only act in and produce their own shows but also create all their own material - could well produce the next generation of city-raised writers and performers.
"I was astonished to find they wrote, produced, directed and acted in all their own shows," says Welsh. "I've seen what they've done and was really chuffed to be asked to help out.
"What's incredible is that they've got no funding, they get on with things rather than make a big song and dance about it. But this is a fantastic resource for young people in this area."
This, he adds, isn't just a creative outlet for those with leanings towards stage and screen. Indeed, the drama company set up by former Lyceum theatre education development officer Steve Small and his Festival Theatre counterpart Ruth Hollyman could, Welsh suggests, provide a grounding for its young participants' entire futures.
"Kids used to leave school and work in the shipyards or in Ferranti but all that's gone," Welsh points out. "It's the entertainment industry and creative industry, things that are internet driven, that are expanding.
"And even if these young people don't go on to be writers or actors or work in theatre, all the communication and entrepreneurial skills they pick up here are transferable. Think what could be achieved if groups like this actually got some money."
If he's frustrated at the financial challenges facing arts and culture at grassroots, it's nothing compared to the patience he's had to draw on while he has waited - and waited - for his latest venture into the world of the silver screen to actually come to fruitition.
But within weeks the film adaptation of his 1996 trio of short stories, Ecstasy, will finally arrive at a cinema near you - a whole decade in the making.
"Ten years," Welsh, 52, groans with a roll of his eyes. "But we've had confirmation that Ecstasy has been selected for the Toronto Film Festival, the biggest film festival in the world, in September. And it'll be out here in October. But it's taken a ridiculous time."
The reason is depressingly simple. "There's no real film industry in Britain any more," he shrugs. "Scottish Screen (now Creative Scotland] has some money to develop scripts but it can't write a cheque for 3 million or 4m to make a film. You need to be casting big names to pull in that kind of money - and that's very hard here.
"So it has to be done through big agents in America. But we were beating our heads against a wall for ages.
"It's sad, it breaks my heart. Right now, I'm writing a film for American TV, which is great fun, but I want to do things here, where I came from and I can't." It means Ecstasy, starring Small- ville's Kirsten Kreuk and Lord of the Rings' Billy Boyd and set at the height of the Nineties' rave scene, was largely filmed in Canada with extras for the movie picked from local people who had to fake Scottish accents and with just the exterior scenes shot in Edinburgh.
Yet while there's a drug-fuelled flavour that may seem like an extension of Trainspotting, this is a film which casts the city in a much more aesthetically pleasing light.
"There are some beautiful shots of Leith," says Welsh, whose 1993 novel and the subsequent film adaptation by Danny Boyle left some in the city reeling with its mortifying depiction of city junkies, sink estates and vomit-strewn pavements.
"The shots are actually so good that the Scottish Tourist board asked if they could use the publicity posters for Ecstasy - they definitely didn't do that for Trainspotting. They're even going to be involved in some of the launches.
"How times change. But some of the shots of the Edinburgh skyline in the film are absolutely fantastic."
The film is, he confirms, definitely worth waiting for. Even ten years.
"It's a strange film, very crafty," he adds. "It's promoted as a cinematic sequel to Trainspotting - what heroin was in the Eighties, ecstasy was in the nineties. So the first half hour is like Trainspotting, there's this very charismatic lead guy, but then it becomes a love story." But while one chapter closes, another begins.
Ecstasy's launch will be followed in January by the US-backed filming of Filth, his 1998 novel which, like most of his other books, shocked - this time with its depiction of a coke-addicted, sexist police officer. Again, its painful gestation period has stretched to around a decade.
In between all that, he's working on the screenplay for a new HBO-based pilot programme inspired by a documentary about Irish gypsy families, who settle their disputes with bare-knuckle fist fights.
That's due to hit the screens in Spring and, if all goes to plan, will be rolled out as a series.
Yet while work and life is played out across the Atlantic these days, it seems there's nowhere quite like home. Chicago may be where he's based, but it's Leith - and, in particular, Easter Road - that he holds dearest.
And just like any Hibs' fan, he keeps one eye firmly on what's happening across town.
With Hearts fans for relations, Welsh has enjoyed a week exchanging pleasantries over the latest Gorgie Road fall-out.
"The texts have been going back and forward and they've been getting a bit of stick. But really, they love all this 'Mad Vlad' stuff.
"They're Hearts fans," he adds with a wicked grin. "They absolutely love being miserable."
Strange Town theatre company has two productions at the Leith on the Fringe - Hex and After You've Gone - both written, produced and starring young members.
Launched just three years ago and based at Out of the Blue arts complex in Leith, it has already produced a string of shows to rave reviews.
"What's unique is that these are young writers and performers and while we give them guidance and feedback, what they do is all their own," says director Steve Small.
The company's new plays are part of a major drive to draw festival goers to venues outside the city centre under the Leith on the Fringe banner.
For details of Strange Town performances visit www.leithonthefringe.co.uk. Further information on Strange Town theatre company can be found at www.strangetown.org.uk.