He appears to be only half-joking when he tells fans his new drama series Crime will “do for British television what Trainspotting did for British cinema”.
In fact, the writer is so convinced the star-studded thriller, which has been adapted from his novel of the same name, will break the mould for British crime drama when it is aired later this year that he gives them a mouth-watering guarantee they won't have seen anything like it.
Welsh reveals a second season of Crime, which has been made by the BBC and ITV-backed streaming service BritBox, is already on the cards well before its launch later this year due to the response to the six-part show behind the scenes.
And the author has not giving up another screen outing for one of his most famous creations, revealing that he hopes to join forces with Robert Carlyle to develop a TV show devoted to Begbie, Trainspotting’s terrifying psychopath.
However, Welsh’s first foray into television will see Dougray Scott star as Ray Lennox, a detective battling drink and drug addictions as he leads a team investigating the disappearance of a schoolgirl.
Laura Fraser, Ken Stott, Joanna Vanderham, Angela Griffin and Jamie Sives will also feature in the thriller, which is set in Welsh’s native Edinburgh, and was shot in the city and Glasgow earlier this year.
Speaking about Crime at the Fringe by the Sea festival in North Berwick, Welsh, who worked on Crime with regular collaborator Dean Cavanagh, says: “We’ve got an amazing cast that we should never, ever have been able to get for the money that we paid.
"It’s almost embarrassing, buy they all wanted to be involved in it. They all loved the scripts.
"After a few drinks I will probably come out with a soundbite like ‘this is going to do for British TV what Trainspotting did for British cinema’. Maybe that’s a bit of hyperbole, but maybe it’s not.
“What I can guarantee is that you will never have seen anything like it on British TV before.
“It’s miles away from a standard cop drama. We’ve broken all the rules.
"The cops are bigger jakeys that the paedophiles and serial killers that they're trying to catch."
Welsh singles James McAvoy out for the stand-out acting performance in any of the adaptations of his work, for his role as corrupt detective Bruce Robertson in Filth.
But he adds: “Wait till you see Dougray Scott in Crime. I’ve never seen him operate at that level before. He is absolutely mental.
“It’s just a mad psychological thriller. It’s very disturbing in a lot of ways.
"I wrote the thing, but when I looked back at the rushes and the rough cuts I was disturbed. I thought ‘what’s my mum going to say when she sees this?’
"But if you don’t feel nervous or get that feeling of absolute dread, that’s when you really start to worry. I’ve got that feeling big-time for this, so I’m hoping for the very best.”
Welsh reveals mixed thoughts about lockdown during his festival chat with broadcaster Grant Stott.
He admits he was dismayed that a film on Creative Records founder Alan McGee missed out on a cinema release, but says the extended break from making public appearances allowed him to complete two new novels, both of which will focus on Lennox.
He says: “As a writer, you’ve always got distractions and you’re always trying to fight against them.
"For me, lockdown has just been a god-send, in a way. I've run out of excuses not to work, so I’ve just been grafting.
“Writers are weird anti-social people who prefer people who don’t exist to real people. It’s given me an excuse to do that.
"I’ve actually written two novels during Covid, but I don’t want to bring them out until things open up again.
"I’ve just got so fed up with all this Zoom crap. It’s horrible. I’m done with it.
"I’ve stopped doing Zoom meetings and podcasts and all that. All my DJ mates would be sending me stuff and I would have to pretend I had listened to it.
“I wanted to write a novel about Lennox, the character from Crime, as a kind of sequel. Then they started filming one of the elements of the book – the kind of Edinburgh back story.
"When I got the scripts for the TV series I realised that I couldn’t bring the book I’d written out because it felt like there was another book between these other two things.
"So I’ve got Lennox books done, which isn’t what I want to be. I don’t want to be a franchisey-type crime writer. It’s not really my thing. But they’re done now and ready to bring out.
"It already looks like Crime could be going to be a second series before it’s actually been screened. There’s been a lot of good responses and big overseas sales.”
Welsh admitted that he had decided to transform Begbie into a successful artist for the 2016 novel The Blade Artist as a way of keeping the character alive.
He adds: “He was still a nutter, but was kind of hiding in plain sight. He had learnt impulse control, but was still driven to violence and still got a big kick out of it.
"He became more cold-blooded, but had the cover of his family and his career. That kept him alive as a dramatic character. He became more interesting.
"We’re talking about doing The Blade Artist as a six-part TV series. I speak to Bobby Carlyle regularly and he’s really up for it.
"We’ve been planning to do something ever since the book came out. We talking about a film at first, but you’ve got a lot more freedom in television now."
Welsh seems more enthused about working in television than having to grapple with the publishing industry.
Trainspotting wouldn’t be published by a publishing house now. Publishing has become like everything else, it’s become mass entertainment. It’s not really about culture now.
“The Scottish vernacular, for example, wouldn’t be seen as a viable thing commercially, as books are pitched to a global market.
“Publishers always used to have little imprints and editors who were interested in publishing stuff that was quirky – they didn't necessarily thing it was going to sell, certainly not internationally.
“Now you have to write into marketing holes. If you think back to 20 years ago, there was just fiction and non-fiction. Now you have to write into genre holes. It’s very much driven by retail and marketing rather than publishers or publishing.
"Most of the executives who work in publishing now would be comfortable working in any organisation and comfortable selling shoes or trainers. They’re not really bothered about selling books, or have that much knowledge about selling books.”
Welsh reveals he has moved back to the UK from the United States since the start of the pandemic, splitting his time between London and Edinburgh, although he has kept on a home in Miami.
He adds: “We’re all fearful of losing connections. Life is moving so quickly now. Everything is changing so quickly. Technology is moving so quickly. Culture is becoming very similar across all places and nations. It’s all being dumped down at the same time.
"To stay relevant in some ways is probably one of the most difficult things a writer can do. The way you can get around that is by not even trying. You have to write to please yourself first and foremost, rather than with a notional audience in mind. If you do that and come from a culture that a lot of people are connected with you should be able to do that.
“One of the reasons that I think I’ve been quite successful writing about Scotland and Scottish culture is that I’ve been both an insider and outsider at the same time.
"I’ve obviously grown up with the culture in Scotland and it’s always been a part of me, but I’ve also had big chunks of time away. The ability to stand outside your culture and look at it almost from another pair of eyes is really interesting.
"When you are young you think: ‘It’s s**** here and it’s brilliant everywhere else.’ But when you move around and go to different places you realise that this is actually the nuttiest place in the world. It’s the most quirky, weird, strange place ever.”