In the darkened back room of a north London pub, a blond-haired woman and her guitar hold a good-natured audience of 30 or so rapt. Sadie Jemmett is headlining Head Music, one of the swath of acoustic nights bubbling up in the capital. It is part of a trend across the capital which has provided a platform for the chorus of singer-songwriters who are now chart regulars, including K T Tunstall, Jamie T, Kate Nash, and many more.
Jemmett, who has played with Tunstall, says that there's an acoustic bandwagon rolling. "It's a very interesting time. The record labels are struggling, so the whole 'big, famous, and taking lots of drugs' thing is over. It's all going back to singer-songwriters, and taking control through the internet."
The 2005 Mercury Prize nominee and acoustic star Seth Lakeman agrees. "I think the growth in acoustic music really is to do with the MySpace thing where people can advertise themselves online. Once they've done that, they want somewhere to play. Sandi Thom was one of the first to do that."
Lakeman won two Radio 2 folk awards this year, but accepts that the current boom is a much broader thing. "It isn't just traditional folk, it's about people wanting to write a song and woo a girlfriend."
The new acoustic boom is a ground-up phenomenon, and "open mic" nights are at its base. These are where anyone who turns up can have a short stint – it's like the early stand-up clubs where Ben Elton, French and Saunders, Eddie Izzard and others played at the start of the alternative comedy explosion. Even someone as successful as Lakeman still plays them: "There are loads of them now. I play an open mic regularly in Glasgow, and the young people there really enjoy live acoustic music."
But Lakeman is also a classic example of how the groundswell in acoustic music, perhaps for the first time since the 1960s heyday of Bob Dylan, Donovan, Joan Baez and Joni Mitchell, is producing a cadre of singer-songwriters who are as at home on the big stage as on the small. "I had a really good example of that recently," says Lakeman. "At the V Festival I was on just before McFly!"
If anyone can claim to be a pioneer of the current open-mic scene, it is Tony Moore. In 1996, this former keyboard player with Iron Maiden and Cutting Crew was plying his trade as a singer/songwriter but was frustrated by the lack of venues.
"The market was all indie, dance, and Manc music," he explains. "I wanted a place for me and all the people I knew who had nowhere to play. So I found a venue in the West End and I put on a night called the Kashmir Club, and within a month we were doing two nights a week. Everyone you now know came through there – Damien Rice, K T Tunstall, Imogen Heap, The Feeling... It was a little moment of zeitgeist. I don't think I created the scene, but I allowed people to flourish and network. I think it inspired other people to play."
Moore's contribution to live music was recognised when, in 2004, he was the sole inductee into the Music Managers Forum roll of honour for outstanding contribution to the British music industry. Since the Kashmir's venue closed he has been at the Bedford Arms, in south London.
But he warns that that legislation threatens the growth in open-mic nights. "Many that wish to put on live music face conditions from local councils like curfews, security on the doors, noise levels, and so on. So although you see more live music, it is against the grain."
The Troubadour Café, in Earls Court, west London, was a Sixties venue where Bob Dylan, Joni Mitchell, and Paul Simon played. Now expanded, it has played host to today's successors including Jamie T, Jack Peñate, and Paolo Nutini. Alex Martin's company, Curious Generation, runs gigs there.
"This time a year ago we weren't doing that many acoustic nights," he tells me. "It was a lot of indie and spiky post-punk. But now, in venues where I would have been doing band-led nights I'm now doing acoustic-led. And acoustic nights used to be about men whining about how their girlfriend left them. Now it's much more varied, and there are many more types of music. There's more soul, for instance."
Back in east London, two miles north of the stage at the Scolt Head, where Sadie Jemmett is finishing her set, is Biddle Bros, an old hardware store that is now a small bar on the Lower Clapton Road – once dubbed "murder mile". Here, Nev Hawkins runs a free night he advertises as "MySpace or Yours". He says that MySpace is crucial to his success. "It means people are able to network with musicians much quicker and connect more easily," he tells me. "My MySpace network, called Songwriters Anonymous, has 1,800 musicians. It has taken me a year to build up. Ten years ago it would have taken me 10 years to do."
Back the couple of miles to the Scolt Head, Jemmett is bringing the Head Music night to a warmly applauded end with her song "Beautiful People", from her forthcoming album Ghosts. "I want to come back and play here again," she says, "it's a lovely atmosphere."
That, perhaps, is the secret. Gone are the bland but aggressive beats of the DJ bar, and in their place are generous, warm spaces for both acts and audience, coming together in human terms thanks to the internet networking that – hang on – was going to keep us apart, wasn't it? Even better, they're the perfect places to spot the next Tunstall, Kate Nash, or James Blunt. Well, two out of three isn't bad...