Richard Mortimer in the Ponystep offices / DAVID SANDISON

Richard Mortimer was the man behind London's biggest parties. Now he is joining the fashion fray, with a magazine inspired by his club nights

Richard Mortimer lives in Clapham, which may come as a surprise, seeing as he has built a career on being the personality – the pulse even – behind the east London party scene.

But after more than a decade of club nights in Hoxton, fashion parties in Dalston and now editing biannual magazine Ponystep from the confines of a Shoreditch office, the East End just got a bit much for him.

"I think London has changed," he says, when we meet. "I don't think you can say for better or for worse, it's just different. It feels quieter."

If the capital is less brash, then it's because of the deafening silence left behind after Mortimer took the decision to close his club night Boombox on New Year's Eve 2007. A honeypot for creative types from the fashion and art worlds, it was a Sunday night drink-and-dancing session that spawned a movement. Or perhaps a movement spawned it. "That whole era was so specific," he continues. "I don't think it can happen again, there's no point trying to force it. Everything was in place and everything just fell together and it worked. I think it's going to be another 10 years before we get that again."

In the wake of Boombox, Mortimer, 31, focused on a new night in Paris called Ponystep, which he then brought home and developed into an online zine. Earlier this month, he hosted a party during Frieze Art Fair to celebrate its second glossy incarnation. So how does a vibrant, over-the-top club night translate into print?

"I'm just trying to do something that feels quite bright and fresh and colourful, but with a slightly more grown-up edge," he explains, indicating the technicolour smile of Dame Edna Everage gazing up from the table. Along with Donatella Versace and Eighties goth star Elvira, she is one of this issue's cover stars. "What I'm trying to do is put forward a different perspective on fashion. It's quite a personal vision."

Mortimer's ventures always are: his successes rely on a keen sense of what his friends, a certain crowd of fashion, art and music industry natives with a peppering of scene-y eccentrics, are looking for. That was how Boombox started, and how Ponystep became reality; the issue has been worked on by and features several of Mortimer's East London crew. "I've grown up with the crowd that's around me," he admits. "I don't think there's a formula. I think you just have to enter into whatever you're doing with such conviction and such self-belief that you have to make something work."

Mortimer is adept at making things happen. At the age of 19, he woke up one day and got on a coach to London with just a suitcase in tow. Having trained as a hairdresser and worked at Vidal Sassoon in Leeds, he soon found a job at a prestigious Mayfair salon. "I grew up on a council estate in Bradford," he says in a voice that betrays little hint of his roots but for the odd soft, flat vowel. "And it was awful. Really grim and depressing. I had in my head from an early age: as soon as I'm old enough, I'm moving to London."

He's part of a cabal of northerners who shaped London's fashion and party scenes during the Noughties: designer Henry Holland and model Agyness Deyn hail from Ramsbottom in Lancashire, Gareth Pugh from Sunderland and Giles Deacon is Cumbrian-born. All were practically part of the furniture in the early days of Boombox at the Hoxton Bar and Kitchen – a classic crowd of latterday Dick Whittingtons come to make their fortune and have a good time along the way. "It's weird," Mortimer laughs, "I think Northerners just end up somehow drawn to each other. But I feel really proud of London and I always have done. I love the fact that you get all these crazy kids, and there's a real sense of energy that you don't get anywhere else."

The capital has a history of infamous parties which become part of the cultural landscape: Steve Strange and the Blitz kids; Leigh Bowery and Taboo; Kinky Gerlinky, Nag Nag Nag and Kashpoint. Mortimer's Boombox was next on the timeline, and the city is still waiting for something to pick up where it left off.

Music writer and DJ Princess Julia, who first rose to fame as part of the Blitz movement, was a regular at Mortimer's night and features in this issue of Ponystep in a series of portraits entitled "Women We Love", as well as an interview with Eighties icon Pete Burns. "Richard has created a printed sensibility which I think reflects the culture we live in," she says. "Tapping into mainstream celebrity and subverting their imagery, and giving a platform to the people behind the scenes with equal reverence. There's an off-the-wall quality but it's not self-conscious or pretentious. There's a lot of love and passion between those pages."

Ponystep is far from predictable and feels less like a fashion mag than a visualisation of Mortimer's little black book. "I've always been obsessed by pop culture," he explains. "I see really mundane things that I think are hilarious and brilliant. A lot of people can be a bit condescending when it comes to mass media, but I give as much support to low-brow things as I do to highbrow things. I've grown up on Coronation Street and Brookside and as a kid I always really liked camp, stupid things. I get a bit bored of these ironic things, it's just taking the piss out of people. That's not very nice."

Being nice is important to Mortimer; making friends and socialising is his métier – perhaps it's his inner hairdresser. "I don't suffer fools," he laughs, "but I think you get places being nice to people. It counts for an awful lot." When he talks about his nights, it has the ring of someone involved in a beloved youth project; Mortimer's events are about building communities and making London as welcoming as it was when he first arrived.

"I started doing nights because I wanted to go to a club where I could listen to the music I wanted to listen to, and I could hang out with all my friends," he says with a shrug. "And the fact that it became so big, it almost started to change a bit. So we did put our emphasis on our friends having priority. At the end of the day, I always wanted it to be that place in Shoreditch where people who had lived round here for 10 years, that felt they couldn't go out because everything had become so gentrified, could go to hang out with all the old faces."

When Boombox became a big noise, in the latter part of 2007, the mainstream pricked up its ears: its DJs were swiped for launch events, Mortimer collaborated on a book of club photography with the likes of Wolfgang Tillmans and Katharine Hamnett, and even Kylie Minogue popped in for a dance when the night hosted the after-party for Gareth Pugh's spring/summer 2008 show. Mortimer was invited to showcase the night abroad, and took it to Milan and to Paris. Given wisdom and hindsight, it seems to have been London fashion's last subversive hurrah before the economy took a tumble.

"We never had any money," says Mortimer, "and you didn't have to pay to get into Boombox. I never made any money from it either. I once co-hosted a launch in Paris with Jean Paul Gaultier, and I said 'What's the point if it's just me coming? I'm not Boombox, it's the regulars, it's all these kids. What's the fee, how many Eurostar tickets can we get out of that? Let's bring Boombox to Paris'."

But this is his abiding feeling: that fun is a priority, not a privilege. At his last event, singer Beth Ditto played for free. "I want to put on something special that they can all walk away talking about and all remember," he explains. "Just something that keeps London being London. I feel fiercely protective of that, and I'm sometimes really scared that we might lose it."

Certainly the scene has changed, and Mortimer has intuited this with his shift into publishing. When money is tight, people are less flamboyant – both Boombox and Ponystep were specifically hedonistic Sunday night clubs. "People became worried about their jobs," says Mortimer when I suggest that plenty of partygoers must have been a little fuzzy of a Monday morning. "You can't call in sick anymore, which is what people used to do."

But the magazine at least offers plenty of gaudy escapism. Alongside more soberly designed style mags, it looks exactly as Richard Mortimer wants it to – the way he looked once too, when he first arrived in the city he has helped to shape. Pony-step is a lairy newcomer, bubbling with enthusiasm and eager to make a good impression.

Ponystep is available now, £12.50