Match.com's sprawl within this sphere is unassailable. Since its launch, more than 75 million people have logged on to the site, which is accessible in 40 countries. Its users exchange 415 million emails a year. It has a Google-like record of gobbling up competition: it purchased OkCupid, a questionnaire-based dating site, in 2011, and also owns Tinder, the mobile matchmaking app founded in 2012.
"We account for 22 per cent of all relationships that begin online," explains Gregory, Match.com's UK manager and European director. "Try this experiment next time you're out for dinner with a group of friends. Mention Match.com and see how many put their hands up and say they met their partner on there, or encouraged a relative to go on it, or know someone who has done. The statistics will be validated, you'll see."
When Match.com launched in April 1995, there were only 25 million internet users worldwide, compared to 2.92 billion today. Having web access at home was considered wildly futuristic. In this world of dial-up modems and chunky desktop computers, Match.com was a flare from the future.
It boasted a clever algorithm, using character traits and interests to pair users with their perfect partner. At first, Match occupied a seedy corner of the internet, ranking in people's minds alongside red light services and dodgy classified ads. The first users were a motley bunch: all of them tentative; some genuinely optimistic, others downright odd.
Bill and Freddie Straus, aged 76 and 72, fall into the first category. The couple from California were among the first in history to go on an online date - and, two decades later, have a long, happy marriage to show for it. "I decided, aged 53, that maybe it was time to get married," says Freddie. "It was very limited, back then - most of the men on it were so old, they could have been my father. I was ready to give up, and then Bill came along."
Bill had been on seven dates by the time he found Freddie. They messaged for a few days by fax and email before speaking on the phone, and went on their first date to a Chinese restaurant in 1996. Freddie remembers friends warning her to be careful; they worried that this innocuous-seeming site might conceal something more sinister, or that the strangers she was speaking to weren't being honest. "The site itself looks different today, but the basics are still the same," says Bill. "When I signed up, they gave me a lifetime membership." Freddie laughs. "Eighteen years of marriage and he's still got his profile on Match.com."
Over 20 years, Match.com has measured public perception of its site. "It started off as sheer geek territory. It was 80 per cent guys, no profile pictures. Stigma was high," admits Gregory, who joined in 2009, after working in advertising and marketing. "But things have changed so much since that we don't bother to measure stigma any more." The statistics bear this out: research by the Pew Research Centre shows that while a third of people surveyed in 2005 would describe online dating as "desperate", that figure has dropped to less than a fifth today.
Jane Stuart told hardly anyone when she set up a profile on the site in 2001. "I was worried that people would think I couldn't get a boyfriend normally," she says. "It was a bit creepy. Those who were doing it didn't admit it. I didn't have a laptop or internet on my phone, so I was logging on in my lunchbreaks."
Then, Jane, a 28-year-old travel saleswoman from west London, came across Andreas Palikiras, a marketing manager from Corfu. Fourteen years later, they are married, with two four-year-old daughters and, aptly, their own Greek wedding business. "It's amazing to have been a pioneer of something that is now so normal," she says.
Though early users were taking a gamble by signing up, the real leap of faith in Match.com's history took place even longer ago. The date was December 27 1992, and Eric Klien, a Las Vegas-based entrepreneur, had just uploaded a 170-point questionnaire for single men and women to his private internet database. It was the product of six months spent pondering the dilemma of dating. "Traditional methods of courting and flirting are risky generally," he wrote in the introduction. "Not only are they risky, but they are ineffective."
Klien's endeavour, called "Electronic Matchmaker", was free to fill in and provided users with a report informing them how many of the men or women on his system matched their responses. Questions ranged from users' horoscopes to their preferred mode of transport, taste in music, cleanliness, condition of their hair, whether they took illegal drugs, how they treated partners and rated their own intelligence. This was the birth of online dating as we know it.
Klien, a somewhat eccentric philanthropist whose interests include cryogenics and the Lifeboat Foundation, an NGO dedicated to the preservation of human life in case of global disaster, now lives in Reno, Nevada. When I track him down to ask about his role in this gargantuan industry, his answers are to the point. "I was interested in using the power of computers to find someone's perfect match," he says. "In person, it is uncomfortable to ask a lot of questions up front, but with a computer a person only has to answer the questions once and then they will be applied to all future matches."
In 1993, Klien sold his questionnaire and the domain name Match.com to the company we know today. "I decided to launch a new project [aiming to build an independent city in the middle of the Caribbean Sea] that ended up consuming all my available resources," he explains, with just a trace of wistfulness.
The buyer was Gary Kremen, a Silicon Valley entrepreneur, who was becoming frustrated by the amount of money he was spending on 1-900 dating hotlines. He purchased Match.com for $2,500 (£1,650) and launched it as a dating service in 1995. Kremen made waves with his first TV interview - dressed in a tie-dyed shirt, sitting on a beanbag, he pronounced: "Match.com will bring more love to the planet than anything since Jesus Christ."
Kremen quickly found a girlfriend online, but lost her to another man whom she met on Match.com - a painful lesson, but at least he knew the site worked. His term at the helm didn't last, however: in 1998, the company was sold. Its current owner, the US media company InterActiveCorp (IAC), bought it in 1999 for $50 million (£33 million).
Officially called "Synapse", but known by insiders as "magic sauce", the algorithm is Match.com's secret weapon. It takes into account a user's preferences - everything from age to hair colour, profession and body type - as well as their actions on the site. So if a woman says she doesn't want to date anyone shorter than 6ft, but frequently looks at profiles of men who are 5ft 8in or 5ft 10in, Match.com "knows" that she is open to meeting them. The results of the algorithm's sums are shown in users' "daily six": a series of tailored profiles that are sent to your inbox each day.
Most of Match's data-crunchers are based in Paris, where the algorithm is constantly being updated. Klien's questions on cleanliness and hair condition have gone, replaced by tick-box surveys on eye colour, music taste and more anodyne hobbies such as reading, watching films and eating out.
Still, many doubt that there is a place amid all things romance for cold, hard calculation. Philosophers have spent centuries studying love, after all, and concluded that it defies logic - so what hope has a computer of matching us with a mate? Indeed, in 2012, a major study, led by Prof Eli Finkel of the Department of Social Psychology at Northwestern University in Illinois, found that "to date, there is no compelling evidence that any online dating matching algorithm actually works". Prof Jerry Mendelsohn, a psychologist at the University of California, Berkeley, tells me that he "knows of no replicated, refereed study by a disinterested researcher that demonstrates an effective algorithm for finding love".
But Match.com insists that love is not its aim. "In the early stages, we used to promise the highest level of love, and we've moved on from that," explains Gregory. "Now, it's all about going on dates and broadening your horizons." Dr Marina Adshade, author of Dollars and Sex: How Economics Influences Sex and Love, believes that if "the true purpose is to encourage online searchers to consider people they might not otherwise have considered if they were left to search on their own... [the site is] like a good friend who forces you to try on clothes that you would never have picked up".
Match.com's biggest user-group is aged 25-44 (56 per cent of all subscribers), while its fastest-growing demographic is the over-55s. There are marginally more men than women on the site (51 per cent, a vast change from the early gender imbalance), and the most common professions are engineers, finance and retail among men; secretaries, doctors and teachers among women. There are men looking for men, women looking for women, serious daters, others looking for flings, and some simply seeking friends.
Tom Scott, 26, a project manager from Surrey, joined the site six years ago. "I have absolutely no confidence in approaching women face to face," he says. "But I've been out with 10 people I met online in the past four months. I've been ice-skating, sushi-making, out for meals."
Profiles on online dating sites are, still, a fascinating mirror to society. A trawl through the 75 million profiles uploaded to Match.com since its inception reveals a rich tapestry of changing fashions, hairstyles and hobbies. It is Kate Taylor's job to study these anthropological details. She is one of Match.com's "relationship experts", and an ideal advert for the site, having met both her first husband in 1999, and her current fiance, online.
"You see so much of the same stuff in profiles - lines like 'I like to stay in with a DVD and a bottle of wine' and 'I love walks on the beach'," she says. "If you put that you like staying at home, going online and watching TV, people can't imagine going out with you."
Research shows that women are less likely to contact men who are far away, older or short; while men are fussier about hair colour than income. "Women smiling into the camera get 15 times more responses than women smiling away from the camera; whereas that's the reverse for men," adds Taylor.
Last year, one of the most extensive analyses of online profiles revealed words such as "surfing", "yoga", "skiing" and "the ocean" attracted people to men; while women secured dates with "sweet", "athlete" and "fitness". Liking the band Radiohead, the TV series Homeland, the film Pulp Fiction and reading The Great Gatsby scored highly among both sexes. Gay men get more interest if they pose outdoors, while selfies are acceptable for women - and mentioning cats in your profile is fine, as long as you don't say "my cats".
Though much of online dating is frivolous, there is, as with all websites, a darker side populated by spammers, con artists, trolls and oddballs. A recent lawsuit filed against Match.com claimed that more than half its profiles are inactive or fake - an assertion the company strongly denies. Last month, Match.com removed a profile purportedly belonging to a former New York police officer dubbed the "cannibal cop", while a woman claimed $10 million (pounds 6.7 million) after a man she met on Match.com attacked her in 2013. The site now runs checks against the sex offender register, and there are measures in place to ensure all allegations are reported to the authorities.
Mercifully, most mishaps are less serious. There is a tendency to exaggerate online: to play up your charismatic, amiable side and conceal your less attractive traits. Because of the sheer size of Match.com, Gregory says oversight on an individual level, beyond weeding out the illegal and offensive, simply isn't possible. "Our members have common sense. We don't get people saying, 'I've gone on a date and it was awful and I want my money back.'?"
At Telegraph Dating, however, a much smaller operation with 55,000 members, there is far more interaction between members and admin staff. "You get people who put up pictures that aren't current, and occasional messages saying things like, 'I've been on a date with this guy who says he's 50 but he's nearer 80,'?" explains Emma Iversen of The Dating Lab which runs the Telegraph's service. "These require delicate conversations with the users - what you say in your profile is a sensitive subject. It can get a bit like a school playground and sometimes we have to step in to calm things down."
A study at the University of Wisconsin showed that four fifths of online daters misrepresent their height, weight or age. On average, women make themselves four kilograms lighter, men tend to exaggerate their income by 20 per cent, and all daters make themselves two inches taller.
None the less, a tranche of serious scientific study into the durability of web relationships has found that they work. In 2013, psychologists at Chicago University showed that marriages that begin online are 25 per cent more likely to last than offline pairings.
The number of people on the net has ballooned in the past decade. As our population ages and traditional familial trends wane, there are more single people in the world, too - an estimated 26 million by 2026, according to the market analyst Euromonitor International - making the pool of potential daters bigger than ever.
Many more women entering the workforce, people being more mobile for work, marrying later and divorcing more frequently have all affected our courtship rituals. Our expectations of relationships have changed dramatically, at the same time as the world has become hooked on the web. Time-poor, convenience-hungry consumers who already live much of their lives online see the internet as an obvious gateway to love. Pragmatism now rules when choosing a partner. It's akin to logging on to book a flight or buying a vacuum cleaner from a catalogue.
Yet Susan Quilliam, a psychologist who runs an online dating course at London's School of Life, says meeting someone online bears remarkable similarities to courtship conventions dating back centuries. "It helps people to focus on background, religious beliefs, life values, life goals, rather than on pure physical appearance. All too often, partners in the first flush of love ignore these essentials. Online is much more like the 'slow' love of a traditional arranged marriage."
But there is a downside. Helen Fisher, a biological anthropologist and consultant to Match.com, calls it "cognitive overload". She points out that "when you have so many choices, you can get into a rat race where you're always seeking something a little bit better". With such an abundance of options, finding someone you want to date can be harder than it was before.
You don't have to be in love to work at Match.com, but it certainly helps. On their first day in the job, employees receive a copy of the "Match Manifesto", a handbook containing the company's guiding principles. "We believe that love is the most important thing in the world," it begins. All staff members - coupled up or single - have obligatory profiles on the site, including Gregory, 41 (though he explains that they're not all "active").
The London HQ is staffed by a team of bright young sparks, their desks cluttered with romantic paraphernalia - framed photographs, paper hearts, lollipops. This is Match's busiest time of year: new members to the site peak between the end of December and the third week of February. But competitors are springing up all the time: VeggieDate (for vegetarians), Cupidtino (fans of Apple products), Clown Passions (you can guess). There are sites for hook-ups (Tinder for heterosexuals, Grindr for gay singles), virgins (WeWaited), and even extramarital affairs. A huge chunk of Match's annual investment goes into innovation; working out how, after 20 years in the game, it can stay fresh. So what's next?
"Imagine someone goes to a Match social [face-to-face singles meetings over cookery lessons, dog walks and golf days]," says Gregory. "They can check in, log the people they meet, and use wearable technology to monitor their pheromones, heart rate, sweat. What a conversation starter that would be: 'You sent my chemistry into orbit.'?"
The King of Love can barely contain his excitement. He's making wild hand gestures, green eyes skipping around the room. "We are constantly looking ahead. We've established the industry and set the pace, but we can't afford to be complacent." He points to a poster on the wall of his office. It's a quotation from Albert Einstein: "The definition of insanity is doing the same thing over and over again and expecting different results."
Funnily enough, the man pulling the strings of Britain's love lives has never tried online dating himself. Gregory met his wife, Sybelle, 13 years ago. "Call me old-fashioned," he grins, "but we met at work." And, with that, he jumps up from his throne and gets back to playing Cupid.
