Bono: The missionary

Bono is the only person to have been nominated for a Grammy, a Golden Globe, an Oscar and the Nobel Peace Prize

There were no fewer than four US presidents sat on the platform, in the rain, looking faintly ridiculous under a hastily assembled selection of umbrellas. This was Little Rock, Arkansas, at the opening of Bill Clinton's presidential library last year. There had been speeches from George Bush Snr, Jimmy Carter, Clinton himself, and the incumbent George Bush Jnr. But there was no doubt from the reaction of the crowd who the star was. Enter the Irish rock singer Bono, and the U2 guitarist Edge.

It was a consummate performance: not just the impromptu rendition of Lennon and McCartney's "Rain", gently mocking the fact that the world's most powerful nation had not reckoned on bad weather, but also Bono's own speech, addressing each of the presidents individually and singling out something good each had done for Africa. And then he sang: "These are the hands that built America." To a British audience it might sound a little cheesy. But in the United States it was brilliantly judged.

The next time the rock star met the President privately, six months later, on the eve of the G8 summit at Gleneagles, it was to ask him to stump up $2bn extra to bring the pledged aid increases to the level the Commission for Africa had said was needed - and on which diplomatic negotiations had stalled. Bush paid up.

Bono's approach reveals something of the singer's personal style. "Bono's in love with the world," said his fellow campaigner Bob Geldof. "He wants to embrace it. I want to punch its lights out." The technique has made the front man of the biggest rock band in the world one of its most successful political lobbyists for change.

That is a lot of superlatives - but superlatives are the environment which Bono is used to inhabiting. U2 has sold some 170 million albums worldwide, making them one of the most successful groups of all time. The band has won 22 Grammy awards, second only to Stevie Wonder. They won no fewer than five this year for their latest album How to Dismantle an Atomic Bomb. U2 has been called by Rolling Stone "the band that matters most, maybe even the only band that matters".

As for the lead singer, Bono is the only person to have been nominated for an Oscar, a Grammy, a Golden Globe and the Nobel Peace Prize. This month he was named by Time magazine as one of the "100 People Who Shape Our World". Even those who don't normally respond to hyperbole have succumbed to his charm. The last pope was keen to swap a rosary for a pair of Bono's ubiquitous shades - which he wears constantly because of a light sensitivity in his eyes, as well as out of pop-star cool.

It is all an unimaginably long way from the 16-year-old schoolboy Paul David Hewson, who spotted a card on the noticeboard at Mount Temple Comprehensive in Dublin seeking musicians for The Larry Mullen Band. Those who assembled in Mullen's kitchen not long after included Mullen, a drummer, Adam Clayton (bass guitar), Dave Evans (guitar) and Hewson (vocals). There were three others too, who eventually dropped out, leaving the four men who were to become U2. It was a world of recherché adolescent nicknames and the powerfully voiced Hewson acquired the moniker Bono after a Bono Vox hearing aid ad while Evans acquired the tag The Edge.

In the depressed Dublin of the 1970s, music was like an alarm call, Bono later said. "At 17 when I first heard The Clash they sounded like revolution to me." Within four years, U2 had a record contract and began the long haul to universal stardom. Bob Geldof remembers the first time he heard them in the States. "It was in a small club in San Francisco early on. To me, there was something recognisably Irish about them - the huge drum, the pounding bass, the enormous gorgeous voice and the powerful rhythm of Edge's guitar, very similar to that of the Irish fiddle. But there was a deep emotional core in it that people respond to, in any language. It was clear they were readily understood by an American audience."

The band embraced America, developing a huge panoramic sound. Delving into American culture they produced their defining album, The Joshua Tree, opening up a generous expansive emotional landscape. But what characterised their work, as their reputations built, was the willingness of the band to reinvent itself. From the straightforward rock of their third album, War, to the distorted sounds of Achtung Baby, and then the techno-influenced album Pop, Bono and his fellows moved through a highly self-conscious journey. "It was always very well-considered," says Geldof. "You need both instinct and intelligence to stay a successful band. They worked at it coherently."

There was about it a post-modern ironic view of stardom. The band's tours became multimedia events which bombarded the audience with all manner of confusing imagery, with hundreds of video screens flashing subliminal text messages and Bono singing not as himself but in a variety of characters which mocked the excesses of modern consumerist culture.

Not everyone appreciated it. Some announced that Bono had become an egomaniac, much as some had missed the point of earlier material - seeing War's "Sunday Bloody Sunday", for example, as a modern Irish rebel song, when it is in fact an appeal for peace among Ulster's warring religious denominations.

For all that, Bono, the band's lyricist, has shown himself unafraid to mix it with politics. During a performance of "Sunday Bloody Sunday", the day after the IRA bombing in Enniskillen in 1987, Bono denounced republican violence and shouted "Fuck the revolution!" - for which one IRA faction reportedly put him on a death list. In London the same year he spoke from the stage of Wembley Stadium of his dread at another five years of Margaret Thatcher. And in the run-up to the vote on the Good Friday Agreement the band played in Belfast to encourage a Yes vote.

But what galvanised him as an activist was a visit, with his wife, to work in an orphanage in Ethiopia in 1985 not long after U2 appeared in the Live Aid concert to raise money for famine-devastated Africa. "Ethiopia didn't just blow my mind," he says. "It opened my mind. On the last day at the orphanage a man handed me his baby and said please take him with you. He knew that in Ireland his son would live and in Ethiopia he would die. I turned him down. That was the rules. But in that moment I started the journey."

It was a journey which took him through the debt-relief campaign of Jubilee 2000 and led him to set up, with Bob Geldof and Bobby Shriver, a member of the Kennedy clan in the United States, his own lobbying organisation Data (Debt, Aids, Trade, Africa) to push in Washington and London for action on Africa's unpayable debts, the Aids pandemic and unfair trade rules that hurt the continent's poor. In 2002 he took the US Treasury Secretary Paul O'Neill on a four-country tour of Africa in an attempt to alter consciousness in Washington. So complete was his commitment, and so thorough was his knowledge of the many-layered challenges facing the continent, that his name was even floated for the job of president of the World Bank last year.

Bob Geldof may have been the motor for last year's Live8 concerts to persuade the G8 to double aid and write off Africa's multilateral debts. But it was Bono whose celebrity was the real magnet that got the pair in to see President Bush and Chancellor Schröder on the eve of Gleneagles.

In the private meeting Bono promised Schröder, who was facing a general election, that he would endorse the Chancellor from the stage at every gig on the U2 tour of Germany. "It will be," he told him," a seriously uncool thing for a rock star to do."

Schröder, who had been dragging his feet on the aid aspect of the Gleneagles deal, agreed to sign up. He knew the value of a Bono endorsement, and the risk of its withdrawal. Bono had made a speech during the inauguration of Paul Martin as prime minister of Canada, in return for a promise of action on global poverty. When Martin failed to deliver enough, Bono went on Canadian radio and denounced the PM who lost the subsequent election.

Some activists thought there was something too cosy about the way Bono and Geldof were mixing it with politicians in these behind-the-scenes meetings. But they came, as Bono told Bush, "with 3.8 billion people in our back pockets" from the Live8 audience which included 157 million people who had signed up for the Global Action Against Poverty in 75 countries. The result was a G8 package that, for all its shortcomings, was better than any political realist could have expected at the beginning of the year.

There was another element to Bono's success in the Bush White House. Since they were teenagers he and Edge and Larry, U2's drummer, have been committed Christians, though they long ago abandoned membership of the hothouse Shalom church to which they belonged in the early days. "He doesn't lay it on you or try to convert you," says Geldof, "but it's at the core of his activism. On rare occasions he talks unashamedly and openly about it. It's what gets him up in the morning."

It is what has given him such purchase among the Republican Right in America. He can trade scripture quotes with the most evangelical of them - except that his quotes are all those about the duty of the rich to care for the poor. Earlier this year he spoke to President Bush at Washington's 54th Annual National Prayer Breakfast where he called for an extra 1 per cent "tithe" of the United States national budget.

In all this he takes calculated risks, Bob Geldof says. "The most important thing for a rock star is cool. That's how they keep their audience." Hanging round with George Bush undoubtedly consumes Bono's cool capital. "But he does it because in a world where celebrity is its own point Bono is a celebrity with a purpose. He's a great man."

A Life in Brief

BORN 10 May 1960, Dublin. Father a Catholic, mother a Protestant who died when Bono was 14.

EDUCATION Mount Temple Comprehensive School, Dublin.

FAMILY Married childhood sweetheart Ali Stewart in 1982. Four children: Jordan, Memphis Eve, Elijah Bob Patricius Guggi Q and John Abraham.

CAREER Singer, U2 (1976 - ). Twenty two Grammys, including Album of the Year and Song of the Year in 2006. Charities and campaigns supported: Amnesty International, Greenpeace, African Well Fund, Support for Aung San Suu Kyi, Data (Debt, Aids, Trade, Africa), Chernobyl Children's Project, Jubilee Debt Campaign, The ONE Campaign, Live 8, Make Poverty History.

HE SAYS "The vanity of the artist is in believing that what they are discovering might be valuable to other people."

THEY SAY "For being shrewd about doing good, for rewiring politics and re-engineering justice, for making mercy smarter and hope strategic and then daring the rest of us to follow, Bono is Time's Person of the Year" - Time Magazine.