Richard is the 33-year-old director of a successful web design company, based in Shoreditch, east London. Tall, good looking and clad in regulation skinny jeans and screen-printed T-shirt, he does not look like a man who – nine years ago – took to spending up to eight hours a day browsing internet pornography, a habit that he says nearly wrecked his life. "Technology enabled my habit," Richard explains. "I got into porn once we had broadband installed in the office [in 2000]. Before that I'd only had a passing interest." He began to stay behind so he could surf porn sites with no fear of interruption, sometimes staying late into the night. "I'd just get lost in it, I'd forget time along with everything else."

Richard believes he was trapped in a vicious circle, lonely without a girlfriend he started using porn, which in turn distracted him from attempting to find a partner. "I'd had broadband installed at home, and had begun to stay in more just to go online. I realised I had a problem when I started making excuses and leaving bars, where I could have met girls, to get home to look at porn."

Late-night online sessions were always followed by periods of intense self-loathing, and it was during one of these lows that Richard stopped staying late in the office and decided to have broadband removed from his flat. "I'm not sure if it was necessarily the result of me quitting but after a month without porn I met a woman. Once I was in a relationship I found I no longer had the same impulse to surf the net. Although I do get urges occasionally," he says, "especially after we have had a row or aren't getting on." Richard was open with his partner and he says that despite her hating porn she was understanding and sympathetic: "She saw things, perhaps, from a more feminist perspective and feels porn is exploitative of women. To be honest, I hadn't considered this much and it wasn't what stopped me. It was the effect it was having on my own life that was my concern."

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According to a 2006 survey by the internet research company Nielsen Online, nine million British men, 40 per cent of the male population, have viewed internet pornography, compared with just two million in 2000. Usage it seems, has exploded in direct proportion to the availability of broadband access.

Ian, a 43-year-old self-employed accountant from West Yorkshire, is back with his wife and two young daughters after an eight-month hiatus during which he lived at his mother's and then a bed and breakfast, while attending counselling sessions. "Because I work from an office at home I had plenty of opportunity to look at filth," he says. Ian takes every opportunity to deride porn, making his new-found feelings towards it as unambiguous as possible: "My work did suffer as I'd get on it in the day, when I wasn't visiting clients. I could be on the computer well into the evening and would have to be dragged down to dinner. Me and the wife had begun rowing about the amount of time I was spending on the computer, even when she thought it was work. When no more money started coming in, she started to suspect something, so I told her I'd got into EverQuest [an online role-playing game]."

Things came to a head, however, when a suspicious Sarah went foraging for the family accounts. "I've always looked after the family finances and have always kept neat files of paperwork. Sarah went ballistic when she saw our phone and credit-card bills."

Ian says it was a relief to confess but describes the months that followed as the worst of his life, especially having to move out and the shame when his extended family discovered the cause of the separation. "Sarah did tell her mother as she didn't really have any one else to talk to, I don't blame her. I think it was like the missing piece of the puzzle for her, it explained why I hadn't been that interested in making love, why I hadn't been so involved in family life and why I was earning less."

When asked if he'd been tempted to enact what he'd been viewing with Sarah, Ian says the thought hadn't occurred to him, as if he never drew any comparison between the women in the images and his wife. "My therapist compared looking at porn to snacking between meals; it fills you up briefly but totally kills off your appetite for the main meal."

Ian and Sarah's rapprochement is strictly conditional. Alongside Ian's continued commitment to the sex-therapy sessions, the PC is now out of bounds outside of work hours. It is also fitted with Cybersitter, an application that filters out adult content. Sarah has also reserved the right to spotcheck the machine's history at a moment's notice. Despite these measures, Ian and Sarah both admit he could get round them if he was really determined. "It is more difficult to avoid porn than to find it these days, but I'm just not interested any more. I nearly lost everything."

Kirsty, 24, from Reading is no longer with her fiancée after he refused to stop looking at internet porn. "If he had faced up to his problem I could have lived with it but he thought everything was fine. Basically, because all of his mates do it and their girlfriends don't seem to care." She met Phil, now 31, through work, at a large insurance firm and the couple moved in together after six months. "About two months after I moved in, Phil started going on porn websites on his laptop. "We'd sit on the sofa, me watching telly and him gawping at porn." Her complaints caused blazing rows as Phil insisted his habit was harmless.

"He wasn't happy with what we did in bed any more. He had become more aggressive. When asked why she went along with it if she wasn't happy she says she felt like she was competing with porn. "After a bit I realised he wasn't having sex with me at all; his eyes would glaze over and he wouldn't look at me and we wouldn't really kiss. He just didn't seem like he was there.

"I moved out following a row after I poured a glass of wine over his laptop. It was better I found out what kind of man he was before we got married. We still work in the same building, though, which makes things awkward."

The solution to lessening demand perhaps lies in divesting porn of its cool. As Richard puts it: "Every porn-star coffee-table book, every exhibition exploring the relationship between art and porn, every lads'-mag sex-tip spread, or pro-porn female celebrity and writer legitimises porn and encourages men to indulge. "Porn," he concludes, "needs to be viewed with caution, as cigarettes are: a guilty pleasure with detrimental effects, addictive qualities and a propensity to cause ill effects on the user and the people around them."

The XXX factor: How to kick internet porn addiction

Jason McClain is a former addict turned therapist who runs an organisation called Quit Porn Addiction, which deals with a growing number of clients who haven't been able to kick the habit alone.

"I've had to move from conducting face to face sessions with clients to encouraging them to use my self-help packs instead," he says. "I simply couldn't keep up with the demand." McClain is also regularly bombarded with requests from the media for interviews – indicating just how mainstream the issue is becoming.

"We embrace internet porn as a convenient sexual fix," he says, "until it becomes seamlessly woven into our daily routines. Porn consistently delivers, and our appetite continues to widen, at the inevitable expense of intimacy and relationships." Escape from personal problems is what drives most men to porn, he believes: "Relationship fall-out and stress at work are the factors my clients mention the most. The economic downturn has already increased the number of enquiries."

McClain also cites the enabling capabilities of broadband and how internet access has removed inhibitors associated with traditional porn; men who were previously too embarrassed to reach for the top shelf can now access a secure supply of porn in their own homes or offices. A survey by Websense, a provider of employee internet management software, found that 22 per cent of men admitted to downloading porn at work, usually an offence worthy of dismissal.

McClain continues: "Supply is definitely creating and increasing demand. And sometimes people turn to porn not because of stress but out of boredom. This is often the case with retirees who start getting into porn later in life."

The arrival of broadband and the growth of internet porn are causing increasing numbers of men far-reaching problems, impacting upon their relationships and professional lives. It is difficult to say exactly what the consequences are for society and equally difficult to develop a solution, especially when the causes of heavy use and addiction have not yet been established and internet porn is so ubiquitous and available.

McCain doesn't rule out the idea of government measures to help solve the problem – in the form of warnings that could appear on pornography websites. "There are more and more alcohol awareness and anti-smoking ads around," he says, "and I think it would be worthwhile to warn people about internet porn. It has addictive qualities and causes ill effects on the user and the people around them." JW