JW Anderson, the NI designer and creative director of Loewe, has opened up on how he turned to smoking and drinking when he first moved to the US at the age of 18 and went from a “polite child to being a mental person”.

The Magherafelt man, the son of Irish rugby hero Willie Anderson, has a host of famous fans, including Jamie Dornan, Jennifer Lawrence, Anthony Hopkins and Cate Blanchett. He also designed Rihanna’s Super Bowl performance outfit last year.

He relocated from Northern Ireland to study performance in Washington DC at the Studio Acting Conservatory.

In an interview with the New York Times Style Magazine Mr Anderson said although his parents were supportive, he recalls their telling him: “Do what you want. Just don’t spend money you don’t have.”

He admitted that instead of focusing on honing his craft, he said: “it was literally Girl Gone Wild.”

Within a week of being there, he revealed he had started drinking and smoking. On one occasion, he explained he went to a party in Baltimore for what he thought was one night; only afterward did he come to realize that three days had passed.

“I’d gone from being this polite child to being a mental person,” he said.

A couple of years later, Anderson, who’d run out of money, returned to Ireland and lived in a rented apartment in Dublin with his dad, Willie, who had been commuting from home to coach the Leinster rugby team.

The designer then got a job as a sales associate in the menswear department at a clothing store which he said “was an exciting time in men’s fashion”.

He then applied to various universities and got accepted into the London College of Fashion.

Between classes, he worked as a visual merchandiser under Manuela Pavesi, Miuccia Prada’s close friend and trusted colleague, at Prada.

Pavesi, who died in 2015, liked to wear pajamas with diamonds; knowing this, Anderson arrived for his interview in a vintage paisley dressing gown that he’d cut above the knee with tight Dior jeans underneath and a pair of Prada boots.

Andrew Webster, an old friend of Anderson’s and the brand image director at JW Anderson, recalled working on a window display with Anderson one day when he disappeared and later found him on the street, wearing a long coat covered with accessories that he’d designed, getting his picture taken for i-D magazine.

“Jonathan was always a bit of an opportunist, really,” said Webster, later adding: “He has this ability to wrap you up into his orbit, and you’re not quite sure how you got there sometimes, but you’re in it.”

Webster also described Anderson as “an overworker”.

“To the point where, even if we’re all fatigued and exhausted, he’s like, ‘I’ve got another idea.’”

He is also unafraid to say how he feels, admitting in the interview that he has, more than once, interrupted a design meeting to tell the team that “everything’s a disaster”; he’s also been known to scrap social media posts and entire campaigns.

The French stylist Benjamin Bruno, one of Anderson’s most trusted creative partners, admited that they’ve had some “extremely fiery and dramatic” disagreements over the years.

“If you don’t argue,” said Bruno, “it means you don’t care.”

Each year, Anderson releases a total of eight runway collections for Loewe and his own brand JW Anderson, traveling between Paris and London.