Yorkshire-born author Adele Parks has sold millions of copies of her novels, which include bestsellers Lies, Lies, Lies and Just My Luck, since publishing her first book over twenty years ago. 

Her latest work, One Last Secret, has shot into The Sunday Times Bestseller List's top 10 in recent weeks and details the dramatic tale of a high-end escort's final job, which should be straightforward but turns out to be anything but. 

While researching the book to create her central protagonist, Dora, Parks enlisted the help of real-life sex workers, paying them by the hour to give her insights on the realities - and potential risks - of working in the world of escorts. 

Here, she tells FEMAIL what she learned from the three very different women who she met up with, including clients' bizarre sexual preferences, and why the oldest profession in the world can be preferable to more conventional jobs that are much lower paid...   

I'm always looking for ways to play with the tropes in my genre.

In crime novels, often the role of a sex worker is largely to be a nameless body in the background: perhaps semi-clad on someone's lap, perhaps dead in a back alley. 

I like writing resourceful, resilient heroines, so I decided for my 22nd novel, a psychological thriller, I would write from a sex-worker's point of view and give her a voice for a change.

I knew that to make the character authentic I needed to interview sex workers. A daunting thought.

I Googled Escort Near Me. Not for the faint-hearted. The search threw up extremely explicit results. Endless women openly lay out their wares and their limits (or rather lack of them). 

Very little is left to the imagination. Selling sex is not illegal in England and Wales. So the process is made very simple. It's a matter of sending an email or making a phone call.

The women advertise a menu of exactly which sexual acts they are happy to perform.

Many boast that they enjoy their work and want to give pleasure. They offer 'Constant smiles', and a promise to 'make all your dreams come true.' 

This phrase led me to coming up with the first line of my novel: 'No little girl grows up dreaming of becoming an izmir escort.
A sex worker. A whore. Keep that in mind.'

A lot of the adverts were clearly written in second language. I offered to pay for their time for a research chat. The three I approached readily agreed; two insisted that I pay only half the advertised rate as I just wanted to chat.

They didn't want to 'rip me off'. Endearing that they were conscious not to exploit me.

First up - let's call her Anya - was heavily made up, she had fake eyelashes and nails, enhanced lips, surgically altered boobs and bottom. She looked like a very attractive manga cartoon. I've seen this look on many young women who are not on the same career path as Anya. 

Her look isn't necessarily a reflection of her profession, more her youth.

She told me she was 24, her advert had said 22. I'm not sure which is true but it struck me as sad that she had to lie. Either to me (to make her look more mature and in control) or to her punters (who want sex with extremely young women).

Anya, like most people I meet, was excited that I'm a novelist and keen to have her stories told. I had prepared questions about how money changed hands, how sex workers look after their sexual health and what they do to try to keep safe. 

She was happy to share funny stories about her work.

Mostly they involved dealing with the personal hygiene of her clients. 'Some of them are really nervous and sweaty, I offer to sponge bath them, like babies.' 

She was less keen to discuss the more dangerous aspects of her job. When I asked if she ever felt at risk or afraid, she shrugged and commented, 'Doesn't every girl'.

She wouldn't elaborate.

Bella was similarly glamourous, except her nails were her own, painted red. 'Men like red. They like pretty and classy,' she told me firmly. I would argue that she was sexy and obvious but I'm not the target market. 

Bella had been a carer but didn't like the risks of working with the elderly during Covid times.

'This pays much better. I have to look at bums in both jobs,' she told me, laughing.

Carly was the biggest surprise and perhaps closest to my character Dora. She charged 50 per cent more than the other two, as far as I could tell she hadn't had any surgery, she was a genuinely pretty and bright young woman with a university degree in digital marketing. 

Rolling her eyes, she added, 'and a whole load of depth to go with it' which maybe explains her choices.

Carly used to work in retail.

She told me: 'I like clothes but I didn't like standing around doing nothing all day. Escorting is the perfect career choice if you don't like standing,' she winked. A well-rehearsed joke.

The women I spoke to were practical, unabashed, humorous.

They had an air of resourcefulness and resilience. They refused to be shamed about the work they do although seemed very aware that practically everyone queues to judge them.

Carly told me about a new phenomenon: the 'pop-up brothel'. 

Pimps rent smart holiday homes and run brothels for a week before moving on, this way avoiding police notice. 

'The girls have back-to-back clients.

No fun, no control. I keep well away. I work within the law. Controlling pimps are the problem.'

'And violent men?' I suggested.

'Yeah, them too,' she admitted.

One Last Secret by Adele Parks published by HQ HarperCollins is out now