Who is Belle de Jour? For a time it seemed we would never know the identity of the anonymous London call girl behind the frank blog.

But in 2009 – in a bid to beat a national newspaper doing it first – she revealed herself as Brooke Magnanti, a research scientist at a Bristol university whose exploits had supplemented her doctoral studies, won her a publishing deal and been turned into the ITV2 series Secret Diary Of A Call Girl starring Bille Piper as Belle.

That was four years ago and Magnanti has since carved out a successful career both as a scientist and a writer – she appears at Brighton Science Festival this weekend to promote her latest book, The Sex Myth.

But she is resigned to the fact she will probably forever be known as Belle.

Via email – she promises she’s not being evasive, she’s just very busy – she tells me, “The blog and books opened a door for me to be a writer and I’ve really enjoyed that opportunity.

“I wouldn’t have minded becoming better known for science but to be honest, that rarely happens.”

It was her career that stopped Magnanti revealing her identity earlier.

She was looking for work when she began the blog, “So obviously, you the first thing that comes up when potential employers Google you.”

Later, it was to prevent her from being fired but as time went on, it became about protecting other people.

“I wrote pretty frankly about the people in my life, not just the clients. There was stuff in there about my parents’ divorce, for example.

Of course, it all came out later anyway.”

She described outing herself as a relief, “Not to have to tell lies, hide things from the people I care about… to be able to defend what my experience of sex work is like to all the sceptics and doubters.”

But it hasn’t all been plain sailing on the other side.

Magnanti has frequently found herself the target of criticism and been called to account for her views.

“It’s been made clear that feminism isn’t a safe space for me. The backlash may be a minority but they’re a very spiteful minority.”

She has faced particular ire for her description of sex work as empowering.

But that was the case for her, she shrugs.

“I’m about as representative of sex work as Gordon Ramsay is of working in a kitchen.

“Getting as many voices out there as possible though will maybe help people to understand that it’s exactly as diverse as any other industry.”

The TV series added weight to the popular idea of Magnanti as “the happy hooker”. It wasn’t exactly a documentary, she says.

“People saw a glammedup picture of Billie Piper and made their assumptions about me.

“Yes, I very much enjoyed the work. But outside of my work life was dreadful.

I was in a terrible relationship, my parents were divorcing and there weren’t many people I could talk to about any of it.”

And although her colleagues were “fantastically supportive” of her, she has found it harder to convince the public that there is more to her than Belle de Jour.

In a way, she says writing the books (The Sex Myth is her fourth under her real name) is an attempt to answer the critics – “The sort of people who put quotes around the Dr bit of the byline or use me as a punchline… not to mention punch bag. I wanted them to know they’re talking about someone who does not suffer fools gladly, who can and will defend herself.”

Among the “myths” she deals with in the book is the misconception that lapdancing clubs lead to increased sexual assault – in fact, she writes, all the available evidence points to a sharp fall in reported rapes in areas which introduce lap-dancing clubs – and how the reported numbers of women being trafficked into Britain for sex work are often wildly exaggerated.

It’s perhaps less surprising to read that women earn far more than men in nearly all areas of the sex industry and earn more working in this field than in an ordinary job.

Would she encourage more women to give it a whirl then?

“Only if they thought they were people who would enjoy it. My standard answer when people email me about this is to recommend against it, the logic being that if some stranger on the internet can talk you out of doing something, you probably shouldn’t be doing it anyway. That goes for pretty much anything.”

Although financially poorer – “I definitely earn less as a writer than as a full-time scientist who was a part-time sex worker” – Magnanti’s life sounds easier and happier these days.

Money was never the main incentive for her and now what’s important is “enough”, she says; having enough money but also having enough time to do the things she loves.

“At the moment that’s sea kayaking, getting out in the fresh air, camping. It’s modest but satisfying.”

She’s now married although won’t reveal her husband’s name. They met online, on Gumtree’s former, euphemistically-titled, “casual encounters” section.

“When I started to fall for him I was in complete denial about where it might go. But I guess I met my match.

“After years of being in bad relationships with people who didn’t accept me, to find someone who did but wasn’t a pushover was worth hanging on to. Also, he makes great stir-fries.”

When she told him she was Belle de Jour, he laughed.

“That was probably the most important thing; he wasn’t impressed and he wasn’t daunted either.

“I’d worked myself up thinking no one would ever want to be Mr Belle de Jour.

I was wrong.”

In the past few years, the couple have moved from Newcastle to Bristol and now to Scotland, where they live in Fort William.

“It’s like having a partner in crime,” she says. “Both of our lives have changed so much over the past few years…to know someone’s got your back in all of it, that’s great.”

Does she ever miss her old life as Belle?

“I miss dressing up and going out, the thrill of meeting new people. Client dates were always much more interesting than the real-life first dates I had.

“But on the other hand the upkeep is pretty taxing.

I’ve become such a slob since leaving the business. It’s kind of nice to hang out in a terrible jumper all day sometimes.”

*Brooke Magnanti appears at the Sallis Benney Theatre, Brighton at 8pm tonight as part of Brighton Science Festival. To book, visit www.brightonscience.com