We're always hearing about celebrity fans,' says Eddie Argos, frontman of chaotic, geeky, shouty, funny and rather brilliant post-punk five-piece Art Brut. 'People say that Madonna likes us.' 'And Ghostface Killah,' adds guitarist Jasper Future. 'He was great when we met him, wasn't he?'

'Oh, he was the best,' says Argos. 'And then there was David Johansen from the New York Dolls. And Frank Black. And Rick Rubin. And Gnarls Barkley. And Wyclef Jean. And David Crosby.'

Future also namedrops Balsac from American comedy thrash metal legends GWAR. 'Apparently, if you ring his house, he has our lyric "Popular culture no longer applies to me" [from the song Bad Weekend] as his answerphone message. How cool is that?'

If Art Brut's celebrity fanbase in the US seems so bizarre, it's because it's difficult to imagine a more defiantly English singer than the tweedy, lank-haired Argos, a man whose appearance and voice recalls a peculiar fusion of Mark E Smith, Jarvis Cocker, Mike Skinner and Ian Dury. 'Someone said we sounded like Stephen Fry fronting Guns N' Roses,' says Argos. 'I liked that.'

Actually, 'singer' is a rather loose word for Argos. His often hilarious lyrics rhyme and scan beautifully but he doesn't so much sing them as bark them out in a blank, wry, Estuary English accent.

'I can't actually sing,' he insists. 'So I just talk. Jonathan Richman was a big influence. And I loved the poet John Hegley when I was younger.'

The band's first album, 2005's Bang Bang Rock & Roll, bagged them four minor British hit singles, serious stardom in Germany and - more curiously - the acclaim of several influential US hip hop critics. It went down well enough for all members of the band to give up their day jobs (until 18 months ago, Argos was a social worker for Camden Council) and start touring the world. Since then, they've played the length and breadth of Europe and North America, as well as slots in Mexico, Russia, Turkey and Brazil.

'We were staying in the same hotel as Franz Ferdinand in São Paulo,' says Argos, 'and we assumed that all these kids outside were screaming for them. Then we realised that they were singing our single Emily Kane. Now THAT was weird.'

Two years ago, they jokingly launched a 'franchise deal' where bands could play Art Brut songs as a numbered tribute band. There are now, rather astonishingly, around 50 Art Brut franchise bands around the world, each assigned random numbers (the Californian indie-rock band We Are Scientists are registered as 'Art Brut 47'). Odd cover versions of their songs have followed: a major Italian indie band have recorded My Little Brother, London grime artist Marvin The Martian released Emily Kane, while Argos is amazed to hear bands in France and Germany perform their songs.

'Our songs translate well because they tell stories using simple phrases. In fact, anyone with GCSE French could probably translate "My little brother just discovered rock and roll" or "Come on, come on, let's have a fight".' It's this simplicity that makes Art Brut's seemingly parochial and defiantly English songs oddly universal.

Their new album It's A Bit Complicated sees them beef up their sound a bit with new rhythm guitarist Future (an old friend of Argos's from their home town of Bournemouth). It also sees Argos finally shaving off his rather rakish moustache. 'I was sick of people thinking I was in my forties,' says the 27-year-old. 'People would come up to me and say: "Why are you in a band with your kids?"'

Argos, like most of the band, now lives in Camden, North London, where he spends most evenings at other band's gigs. He's also managed to befriend nearly all the musicians he loved as a teenager. 'I am truly living my dream,' he says. 'In fact, I'm forming a band called At Last The English Traveling Wilburys.' Instead of Roy Orbison, Jeff Lynne, George Harrison, Tom Petty and Bob Dylan, they've got Luke Haines, 'the bloke from David Devant & His Spirit Wife', John Moore from The Jesus And Mary Chain and, er, Frank Sidebottom. And they're only going to play Traveling Wilburys songs.

'I watched a documentary on the Traveling Wilburys last night - I actually quite like them, you know - and you had George Harrison saying: "Man, what a coup it was to get Roy on board, he's got the most beautiful voice in music." I'm looking forward to making a documentary and saying: "Man, what a coup it was to get Frank Sidebottom on board..."'

'I was trying to explain all this to a journalist from a German magazine who thought we were really cool. He just stared at me like I was mad. I don't think he really understood.'

It's A Bit Complicated is released June 25 on Mute Records.