Earlier this fall, Helen Mirren made headlines for announcing her retirement from on-screen nudity at the age of 70. “That’s the good thing about getting older,” the Oscar winner said in September. “You don’t have to do that sort of thing any more. . . . [Now] my pleasure pillows are purely for my husband.” Although Mirren seemed relieved to be putting her disrobing days behind her, the revered actress did not abhor all of her nude film scenes over the years.

In a new interview, Mirren admits that she did not mind baring all in one project—the 1979 erotic historical drama Caligula. Although it was critically panned upon release, the controversial film starring Malcolm McDowell and Peter O’Toole, and produced by Penthouse founder Bob Guccione, has since found a cult following. As for the reason why Mirren didn’t mind shooting her nude scene in the sexually overt drama: “Everyone was naked in that,” the actress tells People, only half jokingly. “It was like showing up for a nudist camp every day. You felt embarrassed if you had your clothes on in that movie.”

Shortly after filming, Mirren described the controversial picture as “an irresistible mix of art and genitals.” In the decades since, as she’s gone on to win myriad awards for her poignant dramatic performances, the Tony winner has stayed loyal to the project, in which she played Caligula’s wife, Caesonia. “I’ve never opened my mouth to denigrate Caligula,” Mirren told The New York Times. “I was pretty young when I made that—not physically so much as experienced in film. And you know what? It was a great experience. It was like being sent down to Dante’s Inferno in many ways.”

The actress, who was in her early 30s when filming Caligula, said in a recent interview that she didn’t think it was a particularly big deal to remove her clothes for a role when she was young.

“Does it really matter?” she remembered thinking when first asked about appearing topless. “I was doing nude scenes [from] the first moment I started doing movies. . . . It was the era. . . . It seemed to be nothing to get your knickers in a twist over.”

Not to say that she wasn’t self-conscious. “I was always afraid. Always,” the Trumbo star told People. “It’s not fun to be on a film set and be one of the only ones naked.”