Anderson, who plays forthright sex therapist Jean Milburn in the blockbuster Netflix series “Sex Education,” has posted a video on Instagram and explained that she’s “launching a major exploration of women and sex.”

Seated on a burgundy armchair, the 54-year-old actress appeared relaxed as she asked women to send her their “most personal desires” for a book she said she is “curating.”

The Golden Globe winner said: “As women we know that sex is about more than just sex, but so many of us don’t talk about it.

“Our deepest most intimate fears and fantasies remain locked away inside of us. Until someone comes along with the key.

“Well here is your key. I am curating a book of your anonymous letters to me. A book exploring how women think about sex, because sex is about womanhood and motherhood, infidelity and exploitation, consent and respect, fairness and egalitarianism, love and hate, pleasure and pain.”

Viewers were asked if they had a secret fantasy which they would only share with those they “most trusted” — if anyone at all.

The British-American actress went on to say: “Wherever you come from, whether you’re 18 or 80, you sleep with men or women or non-binary individuals or all or no one at all. I want to know your most personal desires.

“Let’s open up this conversation together and create something revelatory.”

Participants were told they can address their letters “Dear Gillian” and send them through an encrypted portal shared in her Instagram bio.

Anderson, who shot to fame in the 1990s playing agent Dana Scully in “The X-Files,” this week wrote an article in The Guardian newspaper explaining the motivation behind her unusual request.

Gillian Anderson plays a sex therapist in the hit Netflix show. Credit: Netflix

In it she cited Nancy Friday’s book “My Secret Garden: Women’s Sexual Fantasies,” which she says “was revolutionary, even provocative” and went to become “required reading for everyone, a multimillion-copy global bestseller, a classic.”

Although published in 1973, Anderson said that she only read the book in 2018 in preparation for taking on the role of Milburn.

“Its unfiltered and painful honesty shook me,” Anderson said.

Since “Sex Education” was first broadcast, Anderson has often been asked about whether women try to confide their sexual secrets and problems in her, she wrote.

“Well, they don’t,” she said. “Which ultimately is what gave me the idea for a book — a ‘My Secret Garden’ for the 21st century, so to speak — that would be revelatory and profound, and inclusive across the board.”

Alexis Kirschbaum, head of Bloomsbury Trade, said in a press release sent to CNN Thursday: “Gillian Anderson’s editorship will help us draw in a wide-range of letters from all corners of the world, and I cannot wait to read the letters she chooses to include in her collection.”