I can feel something soft, warm, and, more worryingly, moist, on my foot. I look down to see a grey-haired man in black PVC shorts, a dog's collar and a pair of German paratrooper boots kneeling in front of me. He has, very cheekily, just kissed my foot. He is in deep, deep trouble. As any well-mannered slave in the BDSM (Bondage, Domination, Submission and Masochism) scene knows, he may kiss only his mistress's shoe. The foot requires special permission. I suspect that Jonathan committed this glaring faux pas on purpose. After all, there's nothing he likes better than being punished.
"That's very inattentive, isn't it Jonathan?" says Mistress Chloe, the self-styled "supreme dominant goddess of all London" who is giving me a crash course in the delicacies of being a dominatrix in a north-London dungeon. Behind us is a large black wheel festooned with buckles, upon which men are shackled, spun and tortured. Next to it is what looks like an electric chair. On the other side of the room is a punishment cage, which Jonathan is gazing at, somewhat wistfully.
It's a wonder that Mistress Chloe, whose memoirs are published this week (sadly, without naming her high-profile clients), can speak at all. She is squeezed into a long black and red PVC dress. Her arms are sweating gently in a pair of PVC evening gloves, and her feet are strapped into a pair of much-kissed, multistorey patent shoes.
She's keen to get on with Jonathan's punishment. "You could put your heel on his neck and ask: 'Why are you here to serve me?' " she suggests. I tentatively place my sensible shoe on his neck, worried that I'm going to hurt him, despite my suspicion that he may not mind.
"Tell him to stand up!" instructs Chloe.
"Stand, Jonathan," I say feebly.
"Then you might want to inspect him. Ask whether he showered before he arrived so he's smelling fresh. You look behind his ears," she says, bending one back. I give Jonathan a cursory sniff. To his enormous sadness, he is agreeably fragrant, and there's no reason for further castigation.
The dominatrix tells him to bend over what looks like a gym vaulting-horse. Mistress Chloe selects a riding crop from her armoury. "You start by spreading the pats on both buttocks," she says, warming up the target area with gentle taps. "You have to ask whether marks are important, because you can't send them away with marks if they're married or they've got a partner, or they're going to go to the gym and be embarrassed."
She hands me the crop and I hesitantly start flicking at Jonathan's posterior. Struck by the absurdity of it all, and a sudden flush of power, I start to laugh. "It can be very funny. I've ended up in hysterics sometimes," admits Mistress Chloe. "I once had a client with his wrists handcuffed above his head, hopping on one leg singing 'Mary Had a Little Lamb', and we were both absolutely in bits."
"Keep going!" comes the muffled voice of Jonathan. "Take it back further! That's it. Keep going, more and more! Even further, bring it down harder. That's it!"
I'm beginning to get into the swing of things, literally. Jonathan, however, starts complaining that he can't feel as much as he would normally because he's still got his shorts on. "You're so not taking them off," I murmur to myself.
"I'm just beginning to feel it," reports Jonathan with just a hint of ennui.
"Now let's move on to the wooden paddle. It's got holes in it to lessen the air resistance, so you can hit harder with it," says Mistress Chloe, giving our slave an almighty whack. "And if he doesn't say, 'thank you, mistress', he's a very bad boy."
"One, mistress, thank you, mistress, two, mistress, thank you, mistress, three, mistress, thank you, mistress..." he counts.
I take over. "She's doing well, isn't she?" says Mistress Chloe.
"Absolutely, very nice. Oh yes, that's just beginning to hurt."
If Jonathan is in his element, then so, too, is Mistress Chloe, alias Claire Mansfield. She became interested in the scene 12 years ago through boyfriends who took her to parties where, if she was wearing "good-looking" shoes, men would sink to their knees and start kissing them.
Mansfield became a professional dominatrix four years ago, when she resigned her job as a market researcher. But why belt people for a living? "The ill-informed think it's about abuse and pain, and in fact it's the opposite," she says. "It's about trust and compassion and love and facilitating a desire for somebody else. Safe, sane and consensual is the code that we abide by.
"There's a psychological dance between a submissive and a dominant; it's very beautiful. A submissive is giving the dominant a gift of submission, and the dominant is helping to facilitate everything a submissive has ever wanted." No sex is involved.
Mansfield says that many of her clients (she has two female customers in the States) are seeking a contrast to their everyday lives. "They're well-heeled, intelligent and they have strong personalities. They have done very well in their professional life and they just want to give up the reins of power to somebody for an hour. If that somebody is a sexy, dominant woman clad in black PVC, then all the better."
What – apart, of course, from her fee of £140 an hour – is the attraction for her?
"I find it very empowering," she replies. "I challenge any woman not to find it seductive to have men kneeling and worshipping you as a goddess. There's a huge maternal element to it, which I enjoy."
Mansfield, who next month is to marry an American website-designer who is also into the scene, doesn't, of course, just torture her clients. Some submissives wish to be her maid, taking particular delight in cleaning her kitchen floor with a toothbrush. She also sees fetishists, the majority of whom have a thing about feet.
"Some people want bare feet, some people want boots or shoes with really spiky heels. One guy wanted my feet to be as smelly as possible. I had to wear my boots for three days and the same pair of stockings, and then take my boots off and rub them over his face. He was in heaven. He said it was the most wonderful experience of his life. It's such a satisfying job."
There are those whose tastes Mansfield refuses to indulge. She gets around half a dozen requests a year from men wanting to be castrated. "It's very much in their heads a lot of the time. They have a self-loathing problem. There are men who will do that, but I don't know any mistress who would, because you are open to prosecution. I think people like that need to see a therapist." Neither would she help the man who wanted to be boiled in a vat of hot oil, nor the Jewish men who wanted her to re-enact an SS interrogation.
By now, Jonathan's penchant seems almost tame. My crash course over, I ask how I fared. "Excellent!" enthuses Mistress Chloe. "Really good strokes. Sometimes it takes mistresses a while to learn the whip properly, but you got it spot-on." I'm not sure whether to feel pleased or worried.
'Dominatrix: a Memoir – the Making of Mistress Chloe' is published by Headline, £14.99Reuse content