At 7.12am on the day we talk, Dr Hilary Caldwell runs naked into Canberra’s Lake Burley Griffin for the annual winter solstice swim. It’s a bracing start to a momentous day. By 11am, she is back at her desk to take another plunge: speaking publicly about being a sex worker for the first time.

Caldwell has never spoken about her sex work to a journalist, and barely to anyone outside her close sphere, with whom she practised what to say. Even her adult children didn’t know until recently, in the lead up to the release of her new book, Slutdom: Reclaiming Shame-Free Sexuality.

“They were really supportive,” Caldwell says. “They knew about the book, but they thought it was to do with my academic work. Now, guess what? Mummy is a sex worker. Coming out to the world doesn’t feel nearly as difficult as coming out to my children. I have far less to lose.”

Slutdom expands on Caldwell’s doctorate, Women Who Buy Sex in Australia, which was the first study in the world on women buying sexual services.

“When I first started that study, people didn’t believe it happened enough to justify a PhD,” she says. “Now people say, ‘Everyone knows women buy sex,’ which I find very gratifying.”

Her book blends academic research, interviews with sex workers and the women who use them, and Caldwell’s own experiences. Her colleagues at the University of NSW, where she undertook her PhD, and the University of Sydney, where her master’s focused on men who buy sex, were unaware that she was a sex worker. Back then, she only felt safe admitting to being a nurse and a sex therapist, which included counselling sex workers in the ACT. But keeping her sex work secret, while simultaneously wanting to lessen the stigma, was a source of stress.

“I was actually challenged twice when standing at a podium: ‘Excuse me, but are you a sex worker? Do you have the right to speak about this?’” she says. “I denied it. Hint to the audience: challenging someone to come out in public is a really dangerous thing to do, because some people will be at more risk than others. I’m thinking ex-partners, custody of children, or homelessness.”

Despite these concerns, Slutdom is a joyous affair, and a mission to work towards establishing a “slutopia”, where all women can be sexually free and there is no gender-based “pleasure deficit”.

One woman she interviewed opined that sex work should be seen in the same vein as self-care and a spa day. Another wanted to learn as much about her desires and her body as she could. Another said that her psychiatrist told her that by seeing a sex worker she had probably saved on therapy fees.

I wondered if there is a golden age when women consider using a sex worker; perhaps in middle age? But Caldwell’s interviewees range from someone who sought out a sex worker the moment she turned 18, to someone who started at the age of 69.

“There’s not a common age, but there is a common stage of where they’re up to in their self-development,” she says. “Are they ready to ditch that shame that they’ve been indoctrinated with?”

Many women who saw sex workers reported that safety was a key reason they paid for sex. Anyone who has browsed a dating app, where so many men describe themselves as “doms” without demonstrating any experience of kink etiquette or after-care, could vouch how important that is. Some women find it difficult to ask a partner to use a condom; with a sex worker, this is a given. Other reported pluses? Feeling free of judgment, more body-confidence and learning new skills.

Women are stringent in doing their research, Caldwell says, but she still has some advice for anyone seeking out a sex worker.

“Look at their website, but also their social media. Look at how long they’ve been around, who’s following them, who they follow,” she says. A good sign, for example, would be if they followed a peak body like Scarlet Alliance, the Australian sex workers organisation.

“One of the red flags – in male-identified sex workers’ advertising in particular – is how much they talk about themselves and in what way. If they’re just talking about the size of their dick, you might hope that there’s more to a sexual experience than that.”

When she first started out as a sex worker herself, in 2003, she placed an ad in the paper. She rented a place separate to the family home, and employed a local security guard for her first few shifts.

“It took a different kind of courage than entering a brothel situation, where there’s camaraderie,” she says. “I’d only met one sex worker in my life, and it was only the week before, at a swingers party. She said, ‘You could get paid for this!’”

Caldwell was not long out of a 15-year marriage, with four young children. Despite her shifts as a nurse, she was struggling financially.

“I’ve always loved sex, and I thought to myself, ‘I could actually be a better mother if I had more money.’ It’s not just food on the table, it’s the school excursions and not having to worry when they ask for something. Then I realised on my first day how much I was going to love sex work.”

As she writes in her book – in true nursing style – she enjoyed “ministering to the skin-hungry”. That was more than 20 years ago, but Caldwell still has clients from those early days.

“I do still get some young clients, especially for educational services and for people with disabilities, but most are my age or older,” she says. “As we all age together, it has become a lot more emotional, with less focus on the body. You have more patience and more understanding of the value of that sort of emotional connection.”

Over the years, Caldwell, who identifies as queer, became more political, energised by protests such as Reclaim the Night and SlutWalk. She hopes for a popular movement around silence and stigma around sex work, that could achieve what #MeToo did for sexual assault.

“I heard a beautiful statement when I was at an exhibition about Wicked Women, a lesbian porn mag in the 80s,” she says. “Somebody said that in the 80s queers had no elders, because the movement was just beginning. So they trailblazed this queer community and acceptance. Now in 2024, they’re the elders. I think sex worker communities will follow that – it’s natural progression.”

It “warms her heart” that there are so many podcasts now of young women discussing sex, and with the rise of subscription platforms like OnlyFans, there is far less stigma around sex work today. Add to that, nearly half of the states and territories of Australia now have a model of decriminalisation.

“My decision to come out now is based on safety,” she says. “I’ve had huge challenges to my privacy and safety over the years. Yet here I am, in 2024, coming out on my own terms.”

• Slutdom: Reclaiming Shame-free Sexuality by Dr Hilary Caldwell is published by UQP ($34.99) on 2 July