The life of ex-drugs baron Howard Marks has hit the big screen in its European premiere on Tuesday night.
The Oxford University graduate from Kenfig Hill, Bridgend, spent seven years in jail in the USA for drug smuggling, and turned to writing after leaving prison.
His best-selling autobiography Mr Nice has been made into a film starring Welsh actor Rhys Ifans as Marks.
Both were attending the screening at the Edinburgh Film Festival.
Marks wrote the book following his release from the Terre Haute federal penitentiary in 1995, where he was sent originally on a 25-year sentence in 1988.
He became a regular on the festival and talk-show scene following its success, and has remained a campaigner for the legalisation of cannabis.
During his time as a smuggler in the 1980s, he had 43 aliases, 89 phone lines and 25 companies trading throughout the world as fronts for laundering drug money, according to his official website.
Speaking outside the premiere, Rhys Ifans told BBC Wales he and Marks were "old friends".
"It's an honour to step into the shoes, the sandals and many other garments of a great man," he said.
"You'd think it would be a huge responsibility [to play him] but I guess it's a testament to how well we know each other.
"It was very simple - put a wig on, talk deep and sound like you've had a smoke."
Ifans added making the film was "great fun" if hard work.
"I'm very pleased with the film and I hope everyone enjoys it. All I know is Howard loves it and I'm happy."
Co-star David Thewlis, who plays an IRA member who does deals with Marks, said it was the most fun he had ever had making a film.
Marks, 64, said being on a red carpet for the premiere was the "most surreal experience" he had had.
Asked if he had given Ifans much help for the role, he replied: "I didn't need to tell him anything. He knew it all.
"I was available. Occasionally he'd call me and ask me a few things.
"I saw [the film] last October. I think it's very, very good; the man's brilliant."
He described the film as capturing the essence of the book correctly.
"I suppose if you analysed all scenes there are differences from reality but, you know, [its] totally faithful in terms of getting the emotions across."
Marks denied it celebrated or glamorised his former activities, adding: "It just mentions them."
The film, which was written and directed by Bernard Rose, is scheduled for general release in the autumn.