Earlier this year one of rock's newest messiahs, U2's Bono, appeared onstage alongside one of its oldest, Bob Dylan, at an outdoor Dublin festival in front of some 40,000 people. And Bono's influence over a new generation was officially confirmed at about the same time when Premier Garrett Fitzgerald invited him to join a committee set up to look at the problems of youth unemployment in Eire. As their native city became a very bleak place with rampant heroin use, unemployment, even child prostitution among the young, U2 had risen from their international success - one of the country's leading exports, it's four most celebrated ambassadors.

Even after traveling the time-honoured course of rock behemoths from the last decade - from being rock's bright new hopes to becoming its most bombastic banner-wavers - U2 signalled some sort of hope and optimism for a Dublin beleaguered by the new depression. In a city where the music scene stagnates around the tradition of Irish showbands, U2 had gone outside and reaped the fruits of world success and brought them home. They are now in a position where they can quietly begin to finance one or two community ventures.

"There are ways we can do things," explains guitarist the Edge, "but we must never be seen as charity, noble boys doling out slops. Just keep our mouths shut and get things done."

Seen in the context of Dublin, even now the purpose, concern and compassion that shone in the early U2 remains still. Even now.

With the view of an outsider, as someone who was swept up on their first LP, Boy, what U2 have come to represent looks radically different. In the aftermath of punk, Boy with its furious mixture of implosion and celebration - the fears, aspirations and adrenalin of four young men stepping out into the world - seemed to herald a new rock dream and a swirl of possibilities.

They may have come from Dublin but in rock's tapestry U2 seemed to have no obvious home or destination. But all too soon their crucial desire to communicate and their relentless energy was directed in the wrong channels. While applauding their moral resilience and commitment, it was sadly predictable to see them embark on endless continental and American treks.

Indeed, consistent touring drew out the bombast, the anthemic rallying cries, the symbolic gestures. Their records had their moments - certainly the vibrant pulsing "New Year's Day" stood up to the best moments of Boy - but in the main they lacked the sensibility to fulfill the debut's promise.

One Saturday night I turned on the box to see Bono clamber over a set of speakers, then unfurl a white flag in their Under a Blood Red Sky video. It was the final irony, this preposterous mishmash of grandeur and blaring lambaste, these shape-throwing sessions weren't what I wanted to be associated with. Where once they had represented Life, Fire and Action, the new rock hopes were looking every bit as crude and vulgar as this generation's Led Zeppelin.

Now on their drive to big fame we meet for the first time in three years, in an annex of Island Records. They've just returned from Australia via Dublin, and in London they will rehearse at Brixton Academy for the European leg of their world tour.

Although they strike me as being just as affable as when we last met on their first British tour, they hold a certain wariness towards interviews. They aren't as keen to be drawn on points of strategy and idealism as before, preferring to let the music speak for itself.

That said, Bono is a gem - immediately exuding the same natural ebullience as on our last encounter. Guitarist the Edge is the calming influence, a rational counterbalance to Bono's sometimes exasperated passion, and at the end of the interview he voices concern that we've concentrated too much on topics other than what really matters - the music itself. Adam Clayton, with his scholarly disposition, came over as surly and cynical. Drummer Larry Mullen, the group's youngest member, is absent as he's decided he's sick of the whole interview process.

With their massive world tour, "Pride" their first Top Five British single and their new LP The Unforgettable Fire, this year U2 are perched on the edge of mega success. They keep the actual figures under wraps but suffice to say the amount of money they grossed last year made sense of the slim returns of their first three years. While no one dares to whisper it, it would seem their plans to make it big, first by playing America's smaller Midwest venues and gradually easing into the large festivals and stadiums has been quite carefully orchestrated by manager Paul McGuinness and their record company.

But it is this endless slog of touring that I feel has drained U2's vigour, a misplaced trust in what it can achieve for the group's music. At this suggestion, Bono's voice cracks into gear.

"We all left school completely uneducated, touring has been our way of learning. It upsets me when I see U2 portrayed in the press as touring, the pressure, the penance. I enjoy looking out of the coach and seeing Denver, Colorado or the run from Edinburgh to Glasgow. I mean, talk to Echo and the Bunnymen, to Simple Minds...these are the bands that are touring, we're not bored by it. This is not a penance."

But nonstop touring can make you lose your bearings, there's a danger of being sucked into the American way, unable to assess what's happening to the band.

The Edge: "Touring has a bad effect on us when we're not being stimulated by it anymore. But with this new LP it's a challenge to reproduce and we're finding the whole idea of being on the road artistically demanding again."

Bono: "The thing about being on the production line, going through the motions - and it's a great criticism of me as a performer - is that whenever the performance is sagging I'd throw the proverbial stick of gelignite into the audience and it would freak the band.

"I've had to face firing squads from the rest of the band on late night phone calls. I would wish not to do that but it was my frustration with the onstage environment, my feeling that a performance should never be boring, that led me to do that."

He likens the banner waving, the speaker stack clambering to an artist's bold strokes. I just saw it as pompish, signifying delusions of grandeur.

"It came from the opposite emotion, it was done out of insecurity. A fear that the music would not stand on its own."

There must be a more honest way of expressing that emotion.

"Yes, that's what we've got to find; I'm not sticking up for myself. We were coming from Dublin, hardly the rock 'n' roll capital of the world. We were putting our shoulders to the door and we developed this muscle, this aggression. Eventually the door opened, but we were still there going Bang! Wallop!"

Later he will correct himself.

"By the way I'm not giving this a whole 'father forgive me for I have sinned' vibe. There was a side to U2 onstage that I'll stand by. I believe conservatism and the English music press reacted against the sweat, the tears, the total thing of the group onstage.

"You think of the '50s and '60s in the U.S. and the white bands of the time, the Buddy Hollys with their shirts and smiles and compare them to the black groups of the time, groups that you respond to. The very reason they were rejected by the establishment was because of the spirituality and the sexuality of it all.

"U2 were the same - it was all too much. The western way is to pick at things, to open little packages and go through the intellect."

The Unforgettable Fire, recorded away from the remorseless grind of the business - first in the ghostly, cavernous ballroom of Dublin's Slane Castle and then in the local Windmill Lane studios - in a cautious way bespeaks a rebirth for U2. Ditching the dullard sameness of Steve Lillywhite at the controls, the group enlisted ex-Roxy Music wizard, ethnic charlatan and Paris recluse Brian Eno and his partner Daniel Lanois to produce the album.

The pairing has reaped benefits, away from the dull litanies of October and the routine agitpop of War, the group's introspective approach has led them to impressionistic landscapes, vast heartlands that their frantic rush into the rock 'n' roll quagmire meant they had bypassed. They've stepped back from the slamming lambaste of War and touched the spirit and celestial wonder at the core of their music once more.

But there is a suspicion that it amounts to little more than an experimental diversion, that the big, bold rock sound will soon surge forth again. Bono dismisses this suggestion.

"If you think there's a period where ODing on rock 'n' roll has damaged the new record, then you're wrong. That is a record totally devoid of the tracks and techniques of rock 'n' roll - which is why it's foxing half the USA as we speak."

According to Adam, over the past five years "every band in the country had been on the phone to Brian Eno," but U2 was the only offer he accepted.

Bono: "All he'd listened to for three years was gospel music. It was the spirit in which it was made that attracted him to the group's music, the sense of abandonment."

Adam gets tetchy: "The question shouldn't be why we wanted to work with Eno but why he wanted to work with us, this pathetic little rock 'n' roll band from Dublin."

The soul/gospel parallel wasn't something I could see in U2.

Bono: "I could relate to it. People talk about the spirituality of U2 and I realised that was part of everyday life in black music. Indeed, Jimi Hendrix was the wildest rock 'n' roll performer, and Janis Joplin would have loved to have been black. I realised though we weren't rooted in black music, there was something in the spirit that was similar.

"With Eno we rediscovered the spirit of our music and a confidence in ourselves. The emphasis was on the moment in this recording, on the spontaneity.

"Like 'Elvis Presley and America' was recorded in five minutes. Eno just handed me a microphone and told me to sing over this piece of music that had been slowed down, played backwards, whatever. I said, 'What, just like that, now?' He said, 'Yes, this is what you're about.' So I did it and when it was finished there was all these beautiful lines and melodies coming out of it."

The title The Unforgettable Fire comes from an exhibition of paintings by the survivors of Nagasaki and Hiroshima, a Japanese art treasure which the group are trying to get shown in Dublin. It also applies to the ugly all-consuming force of heroin which was responsible for destroying a couple of Bono's friends.

"It informs the LP a lot more than people realise. It had a great effect on me. When your friend becomes a junkie he ceases to be your friend, he'll steal from you, he'll fight you."

Another undoubted influence is a lasting passion for the great Martin Luther King, first by way of the LP's lucid closing requiem "MLK" (perhaps the most moving vocal Bono has ever recorded) and secondly in the group's current single.

Bono: "I originally wrote 'Pride' about Ronald Reagan and the ambivalent attitude in America. It was originally meant as the sort of pride that won't back down, that wants to build nuclear arsenals. But that wasn't working. I remember a wise old man who said to me, don't try to fight darkness with light, just make the light shine brighter. I was giving Reagan too much importance then I thought Martin Luther King, there's a man. We build the positive rather than fighting with the finger."

"Pride" and "MLK" are also the most obvious representations of Bono's heartfelt Christianity on the record. Though The Unforgettable Fire relies more on atmospheric textures and fragmented images for its appeal, I wondered if a group with their profound beliefs, and having spent time in America and seen how Christianity is distorted and used by warmongers like Reagan, would like to show the alternative interpretation directly.

Bono: "The best I've learnt about the aspect it to shut up about it. I'm so tired of words, having been to America and seen the faith industry. The three-piece polyester suits, those people frighten me.

The Edge: "Words are a very limiting medium. I don't think it's essential for us to say anything; these things come out best through the music."

As U2 have grown, expanded with corporation like efficiency, so too has their presentation and packaging of the music become inflated into portentous symbolism. Even the magnificent photography of Anton Corbijn on the new LP cover wears heavy on the product of a mere rock band. Again it calls forth images of past behemoths. The song remains the same?

The Edge: "The burnt-out castle is the end of a period. The golden hour is over, the thing that interests us is the faded glory and the creepers, the fact that there is new life getting on in there."

Bono: "It was the antithesis of that Olympian thing you seem to be suggesting."

But you do go in for grand symbolism.

Bono: "But we don't use it in a destructive way. John Lennon's the one that started all that. It was a year listening to him that brought that out. He had a way with words, simple catchphrases and making them mean something to a lot of people.

"With Boy and October I got flak because they were so abstract. So with War I decided to strip it right down. I listened to it for the first time the other day and there was great songs there that you overlooked in your lousy review. I could see how it might have sounded like finger pointing, but we've never pointed a finger at anyone, apart from ourselves."

The War album, which focused more or less on Ireland's troubles, was inspired by playing in America. I castigated it at that time for not doing anything that Stiff Little Fingers had not already done - repeatedly and shoddily.

Bono: "It was only going to America that made us thing about Ireland. You just don't think about it until you have people throwing money onstage during the whole Bobby Sands hunger strike thing. I thought that guy must be so brave, but why? Why be so brave? Why die? There's something not right about this. People were going, 'Yeah! You're Irish!'

"But these people were seeing everything in the black and white about Ireland and they didn't realise it was all in the grey. I would like to see a united Ireland, I believe it is an island. People then say, do you believe in a cause enough to die for it? I believe in a cause enough to live for it. Having had a Protestant father and a Catholic mother I know how grey it is. There are no sides."

Apart from speaking for CND and playing one or two benefits (money from their New York Christmas show will go to Amnesty International), the group are cagey about direct political involvement.

Adam: "These things are all inherently flawed. The way we can best contribute to our time and our generation is just getting down to what we do, which is making records."

Bono: "That's why the idea of The Unforgettable Fire appealed to me because it is a creative thing.

"There is a danger in being a spokesman for your generation if you have nothing other to say than 'help.' That's all we say in our music. It's never sort of, 'Yes folks, here we go, here's the plan.' It's always, 'Where's the plan?' "

While the virtues, even the possible triumphs of the group and War are not in doubt, I still find the flexing of the rock music Bono talked about earlier, indicative of U2's steady route to world domination. Perhaps The Unforgettable Fire is an LP unlikely to reap the full commercial success that could be theirs, but as another world tour stretches before them I wonder if the lure of a crusade is what entices them.

Adam: "I think we acknowledge that stagnation is the worst possible disease. You've got to be threatened and challenged to have an opinion. We didn't want to play the Marquee every night for the rest of our lives."

Bono: "There are easier ways of being big. Only now, after five pieces of plastic, are we having our first hit single. Had we wanted to be the new Beatles or whatever, you would have seen us far more in those papers. It annoyed me to see Paul Du Noyer saying, 'Under a Blood Red Sky was mopping up in the marketplace.' We took our royalties right down so we could sell that record at cut price. Surely the one thing that's clear is that we're not going to take our trousers off to get on the cover."

It's true to say that U2 are a group without any direct tradition. It was a topic Bono broached in a recent edition of Dublin's Hot Press when he interviewed/had a protracted conversation in print with Bob Dylan. The punk explosion had not only freed them of the stifling legacy of '70s Who, Stones, Led Zeppelin, et al, but also cut them off from the valuable heritage of the '50s and '60s, which only now are they becoming attuned to.

"We're lost in space in that respect. We became interested in areas of music - Irish, country, folk. The track on the LP "A Sort of Homecoming" is geographical, but I don't know where it's based. When I look at Van Morrison or Bob Dylan I'm in awe of their tradition, I'm jealous. We haven't got that, we aren't plugged into it."

Still, I counter, they have spawned a tradition of their own. When I first interviewed Bono he was decrying the number of "Johnny Rotten's bastard children roaming the streets." It would seem that now, four years later, with the Alarm, Big Country and a whole slew of Irish surrogates that there's a lot of U2's bastard children roaming the streets.

Bono is emphatic. "Don't answer the question, you shouldn't. Basically Gavin is saying what is the difference between U2 and Led Zeppelin? If we are to sit down and sell him the answer to that question we become salesmen and we're not salesmen, we make music.

"I believe there is a rare spirit to this group but I can't tell you why, that would be wrong. If you don't see that rare spirit to this group then we've failed as a group as far as you're concerned."

I do see a spirit in U2 but I see it falling between two stools, the enlightenment and resource of The Unforgettable Fire, and the possibility that another plunge into the endless touring cycle will drain it, smother it. So I must press the point.

"If you'll excuse me, and with all due respect, that is the sort of question that I don't think we should answer. We're trying to get away from this whole cosmic taking on the world and the music industry and our place in it. Why is music so competitive, Gavin? Just because there's a Top Ten and people see it every week, it's as though it's become a big competition. Why can people not just see our music as part of something else?

"I'm scared of the responsibility of standing in that space," said Bono in the days before he was feted by cheering crowds all over the globe.

Sometimes a little fear in music is not such a bad thing.

© NME, 1984