America's forgotten punk visionary sits suspiciously in the corner of his local pub, waiting to tell his story again. David Thomas has been living in Hove for a year now. His huge frame is in a crumpled grey jacket, his pet whippet sliding around him. The controlled rage of his band Pere Ubu's 1975 debut "Heart of Darkness" seems far away. Then he mentions the Test match - at that stage the result was looking iffy.

"There's a mental weakness in the England team these days," he snarls. "Their whole generation's like that. They should boot the bozos out. They should throw young boys into the firing line, like they did at Stalingrad."

It's David Thomas, all right. He's been the same since he first appeared with the bass drone of "Heart of Darkness" and inspired Joy Division and dozens more. His last record was praised by Damon Albarn, which seems merely to bemuse him. His latest with Pere Ubu, Pennsylvania, is as hard to grasp, as gripping at its best, as all their others. He's never had commercial success, and probably never will. His manager calls him "fanatical, obstinate, petulant, inspired by something, sometimes terrifying". In conversation he's impatient to push his points across, as if he's been waiting too long already. Some of the things he says sound strange, as if he's mad; until you realise he's only right. The jukebox plays hits by lesser bands as we talk.

What he remembers first is where he came from. Pere Ubu are a Cleveland band. They all came from the suburbs, and went to the city's dead heart, the place where the old, abandoned buildings no longer made sense. They watched blasts of industrial gas fill the sky with flame, and lived in the places others hurried to leave. "These buildings to us were like art museums, places of vision," Thomas remembers, "and for a moment you could see behind the fabric of the world and see a perspective that could teach you things, geometries, truths.

"Geography is the only true culture people have. What connects me to Mark Twain is the Mississippi River. The river is an element, a hieroglyph, that always means the same thing, down through history. That's why Bruce Springsteen's best song is called `The River'. The land is the language."

The truth Pere Ubu have been speaking since is that the landscape they loved didn't last. Thomas sees comfort in rivers because the buildings he communed with in Cleveland were pulled down long ago. They only remain in his head. He coined the term Datapanik 20 years ago.

"History's being rewritten faster than it can happen," he sings again on Pennsylvania. He despairs at the ignorance of change, and what it means. "This is not just Cleveland," he states. "Everything is not what it used to be. England is not England any more, and America's not America. There's a homogenisation of culture that's occurring. People mistake it for American cultural imperialism.

American culture was the first to go. The death of Princess Diana was the breakthrough here of the kind of thing that had happened in America. For the first time the media discovered that it was in sole control of reality. To understand the Diana episode, you have only to understand two things: Invasion of the Body-Snatchers, and Day of the Triffids. What you learn from Day of the Triffids is that if you look at something you go blind, and dumb plants can kill you. Media, news, don't look at it. The thing that you learn from Invasion of the Body-Snatchers is that you can't tell who's human any more. But you can't talk about that stuff," he sighs. "There are a lot of other factors that I don't want to get into because they're too ... inflammatory."

The other root of Pere Ubu's quiet, unstoppable rage is the music they grew up with. As a teenager, Thomas saw something powerful in rock music as it threw up off its adolescent shackles, the flowering of "sound as a poetic voice" in Captain Beefheart and Brian Wilson. His band saw themselves as the logical next step in an evolution that had lasted 20 years. It was their manifest destiny to take the torch. Then punk, which they'd unwittingly helped to start, dashed it from their hands. "They just said, `let's be wild adolescents again'," he sneers. "By the early Seventies, the idea that rock had something to do with youth rebellion was gone. But the dog returns to its vomit, and it's been blue jeans ever since."

Does he feel he was denied his destiny? "That next step did happen," he says calmly. "It's just that your idea of history is possibly wrong. We are the mainstream. If I talked about who is the biggest mainstream act in the world today, Pere Ubu might not be the biggest, but we're in the top 20. I hate to talk about myself. But when people look back, they won't see the Beatles. John Lennon will be a forgotten blip. No one will even remember him in 75 years. They'll see Brian Wilson. They'll see Captain Beefheart." He means his heroes are the river. The usurpers currently in power are like those new Cleveland buildings he refuses to see.

Thomas sees being in his band as a test. But as the years grow since their original experiments, it's tempting to see his obsession with transience being played out in Pere Ubu itself - that it's their own obsolescence he's now exploring in his songs. He pauses, sniffing for insults. Then he answers. "What I'm going to say is not substantiated," he says. "It's just a feeling. In November 1978, we knew that we were the best rock band on the planet. You don't get to be the best for long. We're never going to be the best again. But the road we sought to pursue has other qualities to it. Once the boundaries of a continent are outlined, you begin to build the cities. You build the nation."

Thomas's most pressing project is more concrete. Following in the steps of Elvis Costello and Laurie Anderson, next month he'll be in charge of Meltdown, the South Bank's art festival. Collaborators will range from Ubu to Linda Thompson, singing for the first time in years. Thomas has named it Disastodome.

"We're aiming for reality," he explains. "I'll be frying cajun burgers outside the doors. All the participants have strong visions, every one of them is extraordinary. That's me talking sensibly. But see, we code that into calling it a disaster!" He explodes into a choking cackle, and slams his hand on the table, as if it's the most perfect joke he's ever heard. "This is why we're so unsuccessful. This is why, in the end, we are where we are. We thought by calling it a disaster it would entice people in."

`Pennsylvania' (Cooking Vinyl) is released 2 March. Disastodome begins on 2 April. Pere Ubu play the Queen Elizabeth Hall on 5 April.