My mum has a new boyfriend. He’s called Geoff. I’m listening as he explains: ‘I didn’t have to pay because I made her orgasm.’ I’m nine.

Geoff looks at me and then at my mother. I don’t know which of us he’s trying to impress but he’s proud.

Geoff is using the word ‘prostitute’ in the easy way people did back then. If you say ‘prostitute’ now someone in the vicinity will be quick to correct you. They’ll explain how the term reduces a sex worker’s humanity and encourages stigma. Geoff didn’t know that and nor did I.

‘She said she doesn’t usually cum with customers, but because I made her cum, she couldn’t accept any money off me.’

My mum had told me previously, in a private conversation, that Geoff had quite a small penis. And if you’re wondering how that’s relevant, ditto, mate, ditto.

After Geoff had gone home the next day, Mum explained to me that prostitutes never orgasmed with their clients, they just pretended because of the fragile male ego. She told me that there was no way a prostitute wouldn’t charge because they were excellent businesswomen and this was their livelihood.

I apologise that my mum is saying ‘prostitute’ as well. She’s in the past when people didn’t think about what they were saying. She would absolutely say ‘sex worker’ nowadays. But sometimes ‘sex worker’ isn’t the correct language either. If a person has been trafficked, if they are a child, if they are unable to give consent – they ain’t working. We have to be careful with language because it creates the world. I recently heard a true crime podcast describe a woman being kidnapped and ‘forced into sex work’. I’m sure you’re aware that you can’t be ‘forced’ to ‘work’ – that is slavery, and when sex is involved, that’s rape.

I’ve been asked to keep the introduction ‘light’ so *shruggy winky emoji*.

Twenty-eight years later, I heard a comedian talking about PunterNet. ‘It’s TripAdvisor for prostitutes,’ she joked, then missed her bus home thanks to the queue waiting to tell her: ‘We call them sex workers now.’ I went on PunterNet when I got home. It was mostly men discussing the parking restrictions around sex workers’ houses. These men are breaking the law by paying for sex, but they’re only worried about traffic wardens.

PunterNet’s main page is basic and white like your dad with blue and black writing. There are no images. I felt safe to browse. There are reviews and message threads. I read a man’s complaint about a woman’s body odour and wanted to correct his spelling mistakes. I read a review that bemoaned that a woman ‘didn’t smile enough’. I thought this was funny. Men sometimes tell women to smile in the street or in a shop queue. Being told to smile has never made anyone want to. Do the men who say it know how much it pisses women off, is that why they do it?

I know it’s not ‘all men’ who do this, but it only takes a few busy men to mean it happens on a daily/weekly basis to ‘all women’.

Men don’t tell other men to smile, they’d get punched. Telling another man to smile would insult his status, it would suggest that he’s there to please you. That he’s decorative. Telling a woman to smile does the same thing, but men aren’t scared of women’s punches.

YES, sorry – women can be aggressors. YES, some women hit men. This is not a book about how women are always victims and men are always perpetrators.

When I was sixteen my mum had a different boyfriend. It was a complicated situation, he was married. Judge if you must; I certainly did. He would turn up at my house covered in what his wife had thrown at him, his shirts stained with food or smeared with condiments. The marks of her fingers on his face and neck. My mum would be kind to him, which disgusted me, obviously. His wife was a policewoman. She tracked his car. She broke into our house. She dragged him out of bed and beat him in front of my mum and sister. The people who are brutal and scary are created by more than biology.

So what I should’ve said above is: men aren’t automatically scared of women’s punches.

The result of evolution is that women in general are on average smaller and weaker than men, but it feels very sexist to say it. Like I’m criticising my own gender. Like I’m ignoring all the big strong women in the world and all the tiny men. No ‘rule’ about men and women is actually a ‘rule’. It also sounds transphobic, or if not ‘phobic’ then at least trans-ignorant. Discussing sex and biology means stamping with large, insensitive boots over the fragile flower that is individual human experience. There will be a lot of caveats in this book. And one tiny bloke.

Yup.

Going back to Mr Complaints on PunterNet, he’s whinging, ‘She didn’t smile at me once,’ and I think he’s pathetic. He knows this woman does not want to have sex with him. He knows that for absolute definite because he is having to PAY HER to do it. This could not be clearer. He knows this woman doesn’t want to have sex with him and yet he expects her to look cheerful about it? I am laughing nastily to myself, thinking, ‘You can pay her to have sex with you, but you can’t pay her not to hate you.’ Do these men live in a fantasy world where they’re Richard Gere in Pretty Woman? Have they tricked themselves into believing that despite being paying customers they deserve to be desired?

I tried to relate this to my life. Sex work is so called by people who recognise it as a form of labour like any other. ‘Sex work is work is work,’ activists and allies repeat and reiterate. It was Gertrude Stein who wrote ‘Rose is a rose is a rose’ but it was easier for her because no one disagreed and criminalised roses, making their already difficult life harder. The parallel I found is that I go for massages. A form of physical labour, provided by a stranger’s body. I pay people to touch me. It’s weird for me to assess it like that. I think about the interactions I have with professionals I pay to touch me; they ask me what I want from the experience, they speak softly and treat me considerately. How would I respond if they did not follow this code of conduct? If they shouted, if they put loud rap music on instead of goaty panpipes? But I realise that while I understand consumer complaints, I cannot allow them from people paying for sex. I cannot correlate those things. In fact I worry that ‘sex work is work’ has made the people who buy sex feel even more entitled.

As hard as I try to understand the punters’ point of view, they remain psychopaths to me. Unempathetic, selfish. They’re all Geoffs, stupid, self-satisfying Geoffs. Have a wank, I think. Stop wanking in other people. This is a problem. I’m trying to write a book about how evolution moulded human sexuality – my starting point can’t be ‘male sexuality is essentially abusive’ or ‘straight men should all be in prison’, although they are both things I have said when drunk. Researching this book, I’ve realised I am deeply prejudiced. Writing this book, I am attempting to confront that.

In my naivety, I have always wondered how anybody could be aroused by having sex with someone who didn’t fancy them. All the sex I have had in my life AND I’VE DONE IT LOADS I’ve needed the other person to want to have sex with me. If you said, ‘Sara, look over there, it’s Idris Elba. He doesn’t want to have sex with you. He thinks you are gross and smelly, but he will have sex with you if you pay him £80,’ I wouldn’t do it. Being desired is unequivocally connected to my arousal. The bad sex I’ve had, usually it’s because I’ve felt the person didn’t like me.

When I began researching this book three years ago, I didn’t understand that some men become aroused because the other person doesn’t want to have sex with them. There are delusional Geoffs who believe they’re truly desired even in a transactional sex situation and there are also cruel Geoffs. Pain, discomfort or unwillingness turns them on. It makes them feel powerful.

The next post I read on PunterNet was titled ‘WARNING: TRAFFICKED’. It detailed a location, described a woman. Approximate age, assumed race. ‘Give this one a miss.’ The language was blokey and informal. The man believed the woman was not there willingly. ‘She could not speak English’ – matter of fact, not a complaint – ‘she cried throughout.’ I reread the sentence hoping I had misunderstood.

‘Throughout’.

He had done it. Finished. A weeping woman who couldn’t speak his language....