“I never understood why anybody would want to be an artist when they could be a window dresser,” says Simon Doonan, the man who’s been a window dresser — and a lot more — for some 30 years now. “If you’re an artist, you’re stuck in some gallery somewhere. When you’re a window dresser, you’re on the street. It’s democratic. Everyone gets to see what you do. Dogs, children, homeless people.” Then, with wryly British self-deprecation: “I’m ultimately more of a carnie.”

He doesn’t do the windows anymore at Barneys — not since he shifted to the role of the upscale department store’s creative ambassador, after 20 years as its creative director — but with six books under his belt (including “The Asylum,” released in September), a bimonthly column on Slate, a U.K. TV series based on his memoirs (“Beautiful People”) and a flair for colorful shirts, he remains the brand’s most eye-catching figure.

The worlds of fashion, retail and show business bump into each other all the time. And does Doonan have some showbiz tales to tell you, happily dishing over croissants and muffins at Genes, the eighth-floor cafe of Barneys’ East Side flagship.

Did you know, for instance, that as a punky young man just starting out in London retail, Doonan got one of his first gigs working for Shirley Russell, wife of writer-director Ken Russell, in her shop the Last Picture Frock? There she rented and sold off costumes from her husband’s movies including “The Boy Friend,” “Lisztomania,” “The Devils” and “Women in Love.”

That was after the native of Reading, England, went to college in Manchester, and before the move to London where the incipient punk movement prodded him to create the “radical, loony, crazy, edgy” window designs — think holiday displays with rats in little tuxedos — that soon turned the head of the founder of L.A. store Maxfield, Tommy Perse, who lured Doonan out to Los Angeles in 1978.

Back then Maxfield was on Santa Monica Boulevard next to the Troubadour club, and the likes of Natalie Wood, Cher, Joni Mitchell, Jackson Brown, Linda Ronstadt, Chaka Khan and the members of Fleetwood Mac used to shop there.

“It was names, names, names in this tiny hokey little store,” Doonan remembers. “Back then it was not like now, where everyone’s groovy in L.A. What’s happened to L.A. is similar to what’s happened to fashion. It’s gone from being this smaller world to this huge landscape, and you have to just surrender to it.”

He worked at Maxfield for eight years. His favorite story? Being approached by a director he’d never heard of named Martin Brest to design the department store displays that would be featured in his upcoming film. He agreed, except the tribulations of development suddenly turned the movie into a comedy with a new star, and they needed an art gallery, not a department store. Doonan cheerfully volunteered that he could do galleries, too.

“I worked on that movie for a year, and then they said to me, ‘OK, do you want points or do you want a check?’ ” he recalls. “I thought, ‘What are these points? They’re trying to stiff me!’ So I said no, just give me a check, and I got this very nominal amount of money. I remember going to the wrap party and thinking, ‘This’ll be the last we hear of these shenanigans.’ ”

The movie turned out to be “Beverly Hills Cop.” But he laughs off the missed revenue, talking about how he also designed sets for a handful of L.A. plays alongside costume designer Michael Kaplan (“Fight Club,” “Seven,” the new “Star Trek” films). In 1986 he moved East to start his tenure at Barneys.

There he began as a window dresser and eventually rose to creative director in a 20-year stint that ended in early 2011. It was in writing the intro for a photo book of his window displays that he discovered that people wanted to read more of his writing.

For years he had a column at the New York Observer, prior to his current output at Slate. “Windows was a great preparation for writing a column,” he says. “It’s very ephemeral. That’s one of things I liked about windows: It’s very forgiving. It kept changing and changing every week. You can’t be too precious about it. I took the same approach as I did to windows — irreverence, being unconventional, being idiosyncratic — and I applied it to writing.”

He started writing books, too, beginning with “Confessions of a Window Dresser” in 2001.

“We live in an age where women have become so self-conscious and so self-critical that the feminist in me gets very uncomfortable with it,” he declares. “My mission with my writing is always to get women to be less self-critical, and to be sort of like the girls that I used to know in the ’70s in London, who never worried about what other people thought about them. They were very free.”

It’s the kind of customer who would shop at the store with which he’s so closely associated, a smart woman who appreciates the retailer’s “connoisseurial” approach to fashion.

“People say to me, ‘What should I wear to this brunch?’ and I say, ‘Well, why don’t you wear a ball gown? Fuck it. Upstage everybody.’ ” He flashes a mischievous grin. “That’s why probably I give very bad advice, because it’s always so anarchic.”