Moaning Myrtle is the epitome of uncomfortable hormonal adolescence — but she wasn’t played by a teenager.

Shirley Henderson recently reflected on playing the aggressive young ghost in 2002’s Harry Potter and the Chamber of Secrets as a 36-year-old.

“The casting director said, ‘Go for it — and don’t mention your age,'” Henderson recalled in a recent interview with The Independent. She ultimately did “a wee bit of moaning” during the audition, and impressed the filmmakers enough to land the role of the ill-fated Ravenclaw spirit.

Henderson told the outlet that her life didn’t change much after the release of the second film in the wizarding franchise. “I don’t think anybody recognized me at all,” she said.

The actress — who had already appeared in notable films like Trainspotting, Topsy-Turvy, and Bridget Jones’ Diary by the time Chamber of Secrets came along — also detailed her Hogwarts experience in a recent interview with the Radio Times.

“When I was first asked for an audition, I didn’t know who Harry Potter was,” she recalled. “But my sister, who was staying with me, had read the books. Still, I wasn’t convinced I could play a 14-year-old girl because I was in my 30s at the time.”

Henderson explained that she discussed the opportunity with a casting director for the film, who said, “I haven’t told them your age.” So in order to look the part, she presented herself as a much younger performer while reading for the role.

“I went to the audition dressed as a schoolgirl — white shirt, black skirt, ponytail — thinking, ‘This is ridiculous,'” she remembered. “I did my wee bit for them and they thanked me. Months went by and I thought that was it, but then they phoned my agent, asked to see me again, and offered me the part.”

Henderson thinks the age gap between herself and her character can partly be justified by Myrtle’s ghostly nature — the character canonically died in 1943 and has been haunting the second-floor bathroom for half a century by the time Harry enrolls.

“Myrtle is an old person in a young person’s body and because she’s ghosty, there’s a kind of mistiness,” the actress said. “You’re not looking closely at my face, so we could get away with it.”

Henderson went on to act in films like Sofia Coppola’s Marie Antoinette, Bong Joon-ho’s Okja, Danny Boyle’s sequel T2 Trainspotting, and Joe Wright’s Anna Karenina. She also won a Laurence Olivier Award for Best Actress in a Musical for her 2018 turn in The Girl from the North Country, and received a Scotland BAFTA for Best Actress for her work in Southcliffe.

The actress also returned to play Myrtle in 2005’s Harry Potter and the Goblet of Fire and later made a special appearance on the TV competition series Harry Potter: Hogwarts Tournament of Houses.

Henderson can next be seen in the British TV series Summerwater. She also recently lent her voice to Pixar’s Elio and acted in Brian Cox’s feature directorial debut, Glenrothan, which premiered at the Toronto International Film Festival.

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