Would I even vaguely have thought, when I arrived in London, that I might enjoy whipping men? That I might agree to cut them? To sit on their face until they could bear the suffocation no longer? To insert needles into their nipples? To make an art out of hanging them upside down or chaining them to a rack, then electrocuting them?

Of course not. I came to London to become a chef, to learn how to make sticky rice cakes and other pan-Asian delicacies. I wanted adventure, to travel, to escape the narrowness of Canada. But being a chef was nothing like I had imagined. Kitchens were boiling hot, masochistic places. I’d work 16 hours and collapse, only to do it again the next day. I felt unintelligent, unattractive and unfeminine. So I quit and tried to find something else.

It was at a party that someone told me about a magazine called Forum, in which dominatrixes touted for business. Out of curiosity, I bought a copy. Within a week, I had an interview.

Angel, my prospective madam, lived in a mock-Tudor house in north London and practised her trade from a granny flat in the garden. It turned out we had a lot in common. She was my age, and, like me, she was Jewish. She’d been to public school, her father was a prominent lawyer and she loved to talk, quite philosophically, about what domination was — the difference between degradation and embarrassment. Although I had no experience (when she mentioned a TV room, I expected it to be full of televisions, not transvestite gear), she liked me, and let me practise on her transvestite slave, who cleaned and tidied in exchange for a whipping. Soon I had my first client hanging by chains in the dungeon. Then another, and another.

I learnt everything there. I watched videos and I read. I experimented on clients using whips, chains and medical instruments, hung them from racks or locked them in coffins, in handcuffs or in cages. By last year, when I gave up being a full-time dominatrix, I’d seen more than 1,000 men. And earned somewhere between £50,000 and £100,000 per annum.

People often ask what sort of man comes to a dominatrix. Every sort — but particularly, in the places I worked, men from conservative communities who have no other outlet for their feelings. He might be 62, 48, or 18. He might be single, married, engaged, recently bereft. He might want to visit once a fortnight, once a week or just when he’s not shooting a movie, running his veterinary practice, closing business deals or playing football. For some, the £150 treat is only for birthdays. For others, it is a regular compulsion.

What is he looking for? Anything you can think of. He might want to wear a collar and be forced to do humiliating things by a sophisticated woman. He might want to be tortured, or to bring his own mask and tank of nitrous oxide to recreate a dental ordeal that was his first erotic experience. Play out fantasies about angora or pretty feet. Want ball-squeezing, a brutal whipping, bondage and teasing. To be caned. To stare at my shiny catsuit and thigh-high boots through the bars of a cage. To look at me wearing nylons, an army uniform, a cape, a smirk or a snarl.

Why does he come to me? Generally, because he can’t get what he wants at home. Because he knows I understand that he needs to be challenged, humiliated and pushed to his limits. Because he can pay me without questions. Because he knows that when he talks to me openly, I will be utterly discreet. Because I’m kind to him. I let him escape into a world that brings him happiness. Because I will give him the relief he can get no other way.

Why do I do it? That’s a complicated question, and probably one for the therapist’s couch. It’s not about violence or anger. It’s not for sex, certainly. Some dominatrixes blur the line and have sex with their clients. I never do. But I do enjoy it. I’m disciplined in whatever I do: my philosophy degree, ballet classes, writing. And domination takes great dedication and attention to detail. It takes care and love, sensitivity and kindness. If you don’t have those qualities, forget it. So many men tell me that some mistresses are only there so they can get off themselves, to find an outlet for their own power. To hurt men. For me, it’s not like that. Taking someone there is such a fulfilling thing -— and to get really into it, you have to be on that journey together.

People who don’t understand will compare what I do to prostitution. But it’s nothing like it. It would be much easier to give my body, but I’d never have full sex. Yes, the majority of men do come for sexual gratification (although about 10% don’t, because denying themselves that pleasure is the ultimate torture). Sometimes I might give them hand relief at the end. But it is just a part of his body I’m touching, and all within my role.

It doesn’t give me the thrill it once did. For five years, sometimes I’d see six men a day for an hour each. Or eight, for half-hour sessions, when I worked in a West End dungeon. It was exhausting. I was never one of those dominatrixes who made it a lifestyle, who was really into the scene, the whole aesthetic and apparel. For me, domination is not about dressing up, clubs and magazines. It is about exploring the mind — which I still do with three private clients. It’s about discipline. About understanding that, for some people, without pain there is no gain.

Besides, being a dominatrix was never going to be what I did for ever. My family will be pleased to hear that, particularly my mother, who has only just found out about my career. I’m from a nice, conservative Jewish area of Toronto; she’s a teaching assistant and my dad’s an accountant. She just can’t understand why her daughter would want to do what I’ve done — then write about it so explicitly. They think it somehow reflects on them; that people will think there was something wrong with them as parents.

Of course, there wasn’t. It’s all about me. It’s about exploring psychosexual possibilities. It’s about breaking barriers. It’s about understanding what it means to be human. But I suppose there aren’t many mothers who want to read about their child’s sexual experiences in such detail. Perhaps I was naive to believe that they’d understand. Or anybody else, for that matter.

Concertina: The Life and Loves of a Dominatrix by Susan Winemaker (Simon & Schuster £10)

Times recommends

• How I lost the gift of joy for a while
• How to get Coleen Rooney's post-baby body
• The A-Z of winter style rules