It was easily lost in the avalanche of unconfined joy at Barack Obama's ascent to the White House, but perhaps America's most telling symbol of the long, arduous struggle preceding the new president's arrival on the steps of the Lincoln Memorial was a thin, sallow figure in a bushy white beard and woolly bobble hat singing and playing banjo with a vigour extraordinary for a man in his 90th year. Obama's inauguration party got its soul from Aretha, its glamour from Beyonce, its sex appeal from Shakira, its harmony from Stevie Wonder and its sense of theatre fro.U2 . But it was Pete Seeger who linked this key moment in history with the hope and idealism of another age as, flanked by Bruce Springsteen and grandson Tao Rodriguez-Seeger, and backed by a gospel choir, he sang Woody Guthrie's This Land Is Your Land. This was the man who stood shoulder to shoulder with Guthrie singing for many causes, energising union activity, fighting for civil rights and giving a voice to the voiceless. A man who marched proudly with Martin Luther King singing We Shall Overcome, and galvanised the folk song boom which inspired a generation of protest singers led by Bob Dylan. A man who had No 1 hits in America with The Weavers but who was blacklisted and became a cultural pariah - and even briefly imprisoned - after refusing to co-operate with the House Un-American Activities Committee during the McCarthy witch-hunt of the 1950s. A man who has been a thorn in the side of the establishment for seven decades and whose sense of justice has never wilted in the face of fashion, scorn or political pressure. They say today's rebels are tomorrow's heroes and a measure of the reverence in which Seeger is now held may be gauged by the line-up of stars tumbling over themselves to appear at the New York Madison Square Garden charity concert on May 3 to celebrate his 90th birthday ? Bruce Springsteen, Eddie Vedder, Taj Mahal, Joan Baez, Ani DiFranco and Steve Earle among them. Yet, despite his fiercely-held beliefs, Seeger himself is a far cry from the rampaging, truculent leftie of popular myth. The godfather of protest music is actually a gentle, reserved - some would say even distant - figure, devoted to Toshi, his Japanese wife of more than 60 years, and who is surprisingly sanguine about the struggles he has fought. Politics and pacifism were always ingrained in Seeger, who inherited his social conscience from his father Charles Seeger, a musicologist and ex-communist, dismissed as professor of music at the University of California in Berkeley after making loud objections to America's involvement in the First World War. Born in Patterson, New York, Pete dropped out of Harvard University, fell into a job at the Archives of American Music in New York and became immersed in the folk songs he discovered through encounters with figures such as Leadbelly and Aunt Molly Jackson. He was soon playing with them, inspired to take up the tenor banjo in his mid-teens after hearing it at a folk song festival in North Carolina. Seeger was struck by its rhythmic potential and devised his own idiosyncratic style to fit the songs he wanted to sing. "In jazz, all they wanted to do was go clunk clunk clunk and here was this banjo going teenk-teenka-teenk." On March 3, 1940, he was invited to play at a migrant workers benefit concert along with Leadbelly, Burl Ives, Josh White, the Golden Gate Quartet among others. That momentous day - later described by the folklorist Alan Lomax as the birth of modern folk music - he also met Woody Guthrie. They were unlikely companions in arms. Guthrie was a cursing, womanising, wise-cracking, hard-drinking, dishevelled maverick from Oklahoma with a ciggy permanently dangling from his mouth; Seeger was a polite, educated, clean-living, smooth-voiced kid from upstate New York. Yet they shared a common bond, both recognising the potential of folk songs as a vehicle to tell truths about the lives of ordinary folks. Woody was already writing - or at least adapting old folk songs he'd picked up along the way - to relate real tales of hardship, especially those who had lost their homes and livelihoods in the Dust Bowl storms that swept through Texas and Oklahoma in the 1930s. Seeger began to do the same. Together they formed the Almanac Singers, a collective set up to collate, write and record union songs and remained spiritual brothers until Woody became terminally stricken by Huntington's disease. "I must have seemed weird to Woody," reflected Seeger a couple of years ago. "He said, 'This Seeger guy is the youngest man I ever knew - he don't drink, he don't smoke, he don't chase girls'. But I had a good ear and I could accompany him on any song he played. So he allowed me to play with him and within a few months we were getting along pretty well." It was no coincidence Seeger and Springsteen chose to perform This Land Is Your Land at the Obama inauguration, a song written by Woody in 40 as a retort to Irving Berlin's sentimentally patriotic God Bless America. Its socialist intent has often been misunderstood and Ronald Reagan even had the temerity to use it in his 1984 re-election campaign, but Seeger and Springsteen rescued a couple of the edgier verses usually omitted and restored it as a people's anthem. Seeger's own songwriting has been relatively sparse, usually confined to adaptations of existing songs to meet the specific requirements of whatever cause he was championing at the time, be it organising unions, civil rights issues, anti-Vietnam war demonstrations or environmental issues. He'd joined the Young Communist League when he was at Harvard, but left the party in 1950 when the full horror of Stalin's dictatorship became apparent. The classic songs he wrote or helped assimilate - We Shall Overcome, Where Have All The Flowers Gone, Guantanamera, Turn Turn Turn and If I Had A Hammer - not only reflected his status as "independent leftie" but swiftly became an integral part of America's folk song heritage. These were the songs that led a new generation into its battle to create a better world. But, having ignited the folk boom of the early 1960s, Seeger swiftly found himself discarded by it. Its pivotal moment came at the 1965 Newport Folk Festival when Bob Dylan, Seeger's most gifted disciple, abandoned his acoustic guitar, recruited the raucous Paul Butterfield Blues Band to play behind him, and went on stage for a short electric set. The myth was that Seeger, so appalled by Dylan's apparent rejection of all he stood for, tried to chop the cable with an axe. He didn't. What Seeger actually said was: "If I had an axe I'd cut the mike cable," before retreating to a field to escape the barrage. "I hated not being able to hear the words," he said. "He was singing a good song. Maggie's Farm is a great song and later, when I saw the words, I knew it was great." As brief as it was, Dylan's set that night transformed the musical landscape. The Beatles were already revolutionising pop and, after Dylan had plugged in, the folk movement - and with it the protest boom - was dead as a serious political and social force. Refusing to compromise his beliefs, Seeger kept playing his banjo, never wavering in his trust in folk song as a means to unite spirits, exhorting his audiences to sing along. He was sometimes ridiculed as a result. Not that it ever bothered Pete Seeger. He kept making records and playing concerts and putting his weight behind things that mattered. And then, ever so gradually, the mood shifted again. Dylan had never ever uttered a word against Seeger and when in 2005 he spoke of him in admiration and even awe in his autobiography Chronicles and the Martin Scorsese documentary No Direction Home, Seeger's place in musical history began to be reassessed. Springsteen's tribute album The Seeger Sessions the next year confirmed Seeger's new status as a bona fide American treasure, affable but defiant and unyielding to anything but his own conscience and integrity. That is why the old man in the bobble hat with the croaky voice at the Obama inauguration was one of the true heroes of the occasion. * The National