Like most introduction agencies, Loving Links expects its members to have the traditional GSOH and a lot of on-tap TLC. However, if you WLTM a "Genuine Single" man or woman, you're out of luck: This is an agency specifically for married people seeking extra-marital relationships. And one that's fairly choosy about exactly whom it will take on. So what else, apart, obviously, from a husband or wife, do you need to commit adultery to Loving Links' exacting standards? I met MD, David Miller to see if I might fit the bill.

"Oh, God, no! You smoke!" was his first objection. "So?" I asked. "It does severely limit the number of women we can put you in touch with. It's rare we get smokers - when you're conducting a clandestine relationship, the last thing you need is to go home reeking of your lover's brand of tobacco." For similar reasons, he explained, those suffering from the "Lynx effect" or a tendency to act on Impulse are also advised to desist or scrub well beforehand.

Mid-50s, expensively dressed, and looking very much like someone who might like to audit your accounts, Miller is actually a trained psychologist, and therefore well experienced in assessing personality ("A lifetime of philandering has also helped."). These assessments are generally held in some plush location - in my case, the Palm Court of the Langham Hilton, London - presumably to determine, in the first instance, whether you can make it through the lobby without being intercepted by the doorman as an undesirable.

"I reject about three out of five of those I interview," said Miller. "There are the obvious things: Bad teeth, boring people, those who have no sense of humour, style or charm. I tend to automatically reject those who are markedly overweight - especially men - unless they compensate by being very charismatic. And I avoid women who are obviously neurotic or who come across as clinging or over-dependent. Then, of course, there are the sort of people - men in particular - who are looking for something we don't actually offer. They simply want sex.. You use a call girl or escort service for that, not us."

So who are his clients?

"People who, without blinking, can put my fee on their Visa card: Lawyers (I jokingly say we have a corporate rate with the Law Society), company chairmen and chairwomen, management consultants, and the occasional - very occasional these days, in fact - dotcom millionaire. We're talking salaries of upwards of £60K. Of the 700 or so on my books, the ages range from mid 30s to mid 50s. I even have one woman in her 70s."

So what do they get for their money?

"Over a two month period, we will guarantee to introduce you to at least three or four people who, in our judgement, are compatible and who, like yourself, are ultimately looking for a sexual relationship. There's no guarantee, however, that things will turn out that way. We are primarily selling friendship. Friendship which may, or may not, at some moment, develop a physical side. If it does, it's purely down to your own charm and sexual chemistry."

But a charm and sexual chemistry which, surely, could be equally apparent in any bar, nightclub, or other public place? Why pay - and pay highly - to access it via the agency?

"Yes, you could meet someone in a bar and click. But there's always going to be a moment when you have to take a deep breath and admit `I'm married with two children.' How will he or she react? Possibly very negatively. With us, there's no confused agenda. You both sign up because you are married, so you both know where you're coming from. Therefore all the bullshit, all the double-duplicity, is gone."

So what, ultimately, are people looking for out of these "extra-curricula" activities?

"Something better, or different, than they can get at home. Maybe they're not getting the affection and attention they crave, maybe they aren't satisfied sexually. Generally, both sexes are seeking friendship, romance, and sexual adventure. I'll tell you what really drives our business - lifestyle magazines. All those `Six Exciting Sex Tips to Try Tonight' articles. But who with? Your husband who snores, you've been married to for 11 years, and who'll only have sex with the lights off? No chance. With a lover, however, you can try these things."

What about the deception aspects, though? How does he answer the charge that his agency encourages infidelity?

"But you're not going to come to me unless there's already some sort of dent in your relationship. Besides, marriage isn't hugely about sexual fidelity, is it? Some are, but for the majority of our clients, marriage is about mutual financial and emotional support and a loving environment for bringing up children. People who use us fulfil those expectations in spades. If they don't - if I believe there's even a slight possibility that by using us, a person may threaten their marriage - then I'll refuse to take them on.

"As it is, though, our clients know exactly what they're doing and are safeguarded by being under our umbrella. If anything, by having an affair, they might actually be working out their frustrations, and return to their partner refreshed and happier. I believe I've saved more marriages than I've scuppered."

Robert, 54, is a successful barrister who's been married for over 30 years. Though he heartily recommends marriage as an institution, he feels that, as some sort of one-stop-shop for sexual fulfillment, it has its limitations.

"I married - as, I believe, everyone did in those days - with pre-conceived ideas about long-term fidelity and all the usual happy-ever-after clichés. But we found as the years went on that there were, shall we say, `incompatibilities'." One of whom successfully seduced him in Chambers during a lunch break, thereby initiating a life of on/off love affairs. "I got the taste for it, I suppose."

But why go through an agency, given the apparent ready availability of suitable candidates at work?

"Security and status. I'm not ruling out the possibility of again having a relationship with a person who's single, but there are attractions in meeting someone in the same situation as yourself: You both know you must be discreet about the whole thing. In addition, because that person is vetted in advance by an agency, she's more likely to be on your wavelength."

So what is he looking for?

"I want somebody who, above all, is a friend, and then a lover; that's intelligent, affectionate, and with whom I share mutual interests. You have to find this Nirvana between casual sex, which I find pretty bloody awful, and a deep and meaningful relationship. You've got to be somewhere along that continuum. It's quite difficult to do. In my case, I either get too involved, or else it's not involving enough."

So does he believe all sexual relationships have an expiry date?

"Within any long-term relationship, not just marriage, I believe it's very difficult to keep a vibrant sexual relationship going. It's almost a contradiction in terms. But some lucky couples do manage to have that spark forever, though I don't know of too many."

How many partners has he found through the agency?

"In three and a half years, I've had four, ranging from a minimum of three months to a year, maximum." Sequentially or concurrently? "At the moment I'm seeing more than one person, but that hasn't been my usual rule. I prefer to find someone of whom I can be fond - to a degree - and want to be only with them."

And what does his wife think to all this? Or doesn't she know?

"My wife is aware that I've had affairs, and we haven't had sex for a long time since she found out. Which, in itself, has made me more needful of these external relationships. But it's not something the two of us talk about. She assumes I still do it, but seems to have reached the stage where she turns a blind eye. In fact, I'd say that it's actually strengthened the bond between us. There's been a reality check: Through this, we now know that we're still fond of each other and, in a number of ways, that it makes more sense for us to stay together."

Gabrielle, mother of three, had been married for 27 years when, "One Saturday morning, I just sat down with my husband and said `I don't love you any more, and I'm sick of pretending.' There was no special reason. Like plenty of couples who'd been married for years, we'd just lost the plot sexually and emotionally. "

Her blunt confession did, however, start to trigger "dormant feelings". "I'd been through all these years of marriage, dead from the neck down as far as sex was concerned. Now I was like a bitch on heat. But my body was ready, my head initially wasn't - it was like a raging war in there between Barbara Cartland and Jackie Collins. Part of me wanted just sex, the other half craved romance and love."

Jackie Collins won the first round, and, in a scene straight out of "Confessions of a Plumber", Gabrielle bedded a man who'd come to fix her shower. But, although the sex was satisfactory (and he apparently made a decent job of the shower, too), she came to the realization that "I needed a lover, but I didn't want just anybody. I'm one of those women who can't have a sexual relationship with a man without being in love with him."

Which is where the agency entered her life. Or rather, half of it. She still maintains the facade of a married life for the sake of the children, but sees men friends as and when. "My husband is a very loyal man and has staying qualities. He knows, but he doesn't know, if you see what I mean."

Having affairs has also changed her view of men for the better.

"I came out of this sexual tunnel I'd been in for 25 years, not really knowing what made men tick, thinking that basically, they were mostly shallow and just after sex. But when I actually started meeting and talking to them, I've found that all the men are caring, genuine, and up-front. Which just goes to prove the old adage that the nicest men are the married ones."

According to Loving Links' assessment, I am of reasonable height, reasonably articulate, and reasonably well-dressed. Lookswise, if it's reasonably dark, I could maybe pass for Ronald Coleman. (Until someone turns up the lights, then it's more David Coleman.) So what sort of woman could I reasonably expect the agency to fix me up with?

Renate, as it turned out. She's 45ish, married 15 years, has a 10 year old daughter, and an average of 6.5 lovers per year. Imagine a slimmer, somewhat taller Ruby Wax. We both arrived fashionably late at a Chinese in Soho. My choice, but a bit down-market for her: She prefers places like the Langham Hilton, the Waldorf, and the Lanesborough. Nevertheless, for the occasion, she wore an elegant Versacci number with matching nicotine patch. (It didn't stop her helping herself to my Dunhills, though.)

"I haven't slept with my husband for seven years," she explained. "He is incredibly bad in bed. `Women are too demanding,' he says, `I prefer to satisfy myself.'" In his spare moments, however, he works in a university physics department. Renate is "something in the City", which, whatever it is, has made her independently wealthy. Obvious question, then: Why not just divorce - she'd almost certainly get custody of her child - buy her own place, and lead a carefree, single life?

"I don't need to divorce because I have so much freedom, anyway. Besides, no amount of would-be happiness in the future could ever justify what divorce can do to children. My husband and I both come from separated families, so we're well aware of the consequences."

But isn't the atmosphere somewhat strained at home?

"No. I get on very well with my husband. He's intelligent, good company, with an excellent sense of humour. It's simply that we have separate bedrooms - mummy's room and daddy's room. Which is no problem, because we both like our own space and have our own lives."

Does he know about her extra-marital activities?

"He's a highly intelligent man - of course he knows. But he realizes that it's best to accept the situation. `You don't seriously think I'm getting laid every time I go out, do you?' I once asked him. `Perhaps not every time,' he said. That's about as close as we've ever come to falling out over it." Suppose she suddenly looked across at one of the other tables and saw her husband with another woman? "He's allowed to do whatever he wants - I've told him that."

Why go through an agency?

"I'm looking for two things in a man: Good company and great sex. Possibly I'd get lucky and meet a man through work or at a bar that could provide both. Maybe. But with the agency, I'm guaranteed it. David gets feedback from his women as to exactly what the men are like and so can match my requirements exactly."

Perhaps one day, matching them so exactly that she falls for one of them, big time?

"It couldn't happen. I suffer from - as a friend put it - the `neurosis of abandonment'. In other words, I approach every relationship knowing that it isn't going to last, because, if it did last, I'd be too afraid of it coming to an end. If that makes sense."

So, if anything, the marriage is actually providing a point of stability?

"Exactly. The more I meet other men, the more I appreciate my husband's qualities. And I believe this applies equally to other men and women. Marriage based on good mutual understanding and where the sex is good and sustained over decades is very rare. So I'd say, if you are bored or unhappy sexually, then go for it: As you meet other people, you usually find that the person you're living with is in fact quite good in comparison."

Which appears to be the overall message: Having affairs, if not actually strengthening the marriage, then at the very least makes it a survivable experience for both parties. It's not that the agency members are serial bed hoppers - they're ordinary people who, through no fault of their own, have had something go seriously wrong in their relationships. Something which all of the Relate counsellors in the world wouldn't be able to put right. But, like all of us, they nevertheless still crave affection and friendship. So what to do? Suffer in silence and thereby probably aggravate whatever it was that poisoned the marriage in the first place, or look for solace outside? And if, by going through an agency, they afford themselves, and their families, an extra degree of security, so much the better.

020 7602 8727

www.lovinglinks.co.uk

Loving Links offers two type of service. For £75 you can place a personal ad in their magazine, which is distributed to all members. This will be as effective (or otherwise) as any personal ad, except you can be certain that any respondent will, like yourself, be someone who's married and seeking an affair. It's then up to you to fix up a date and meet, abiding by the usual safeguards for these sorts of things.

The second, or de-luxe service, costs £1,500 for two months. Here, assuming you pass the preliminary interview, you be matched with a minimum of three people who, in the estimation of Miller and his team, most closely meet your requirements.