The Rastafarian artist is regarded by many critics as Jamaica’s greatest living singer-songwriter yet does not have the fame to match. Clothing the iron fist of socially-conscious protest songs in his velvet tenor, he deserves to be seen as reggae’s Sam Cooke, his greatest influence.

His 1970 album “Songbook” is one of the greatest collections from Clement “Coxsone” Dodd’s famous Studio One, containing Marcus Garvey-inspired songs of African repatriation such as “I’ve Got to Go Back Home” and “Unchained”. Andy compositions have been covered by Ms Dynamite, UB40, Ocean Colour Scene and The Specials. He hit the British charts with Marcia Griffiths in a reggae duet of “To Be Young, Gifted & Black”.

But after a life marked by “consistent pain”, from the psychological scars of a difficult and unhappy childhood to health problems that required serious chest surgery, he says he could not have withstood the pressure of fame placed on Marley and Cliff.

Instead at 68 he is brimming with optimism and bonhomie. He is “phenomenally overwhelmed” to “remain relevant” to a musical movement that fills him with pride for “a nation that is just a speck on the map”. Having just performed in France, he will appear alongside Jimmy Cliff at London’s O2 on the 50 th anniversary of Jamaica’s independence on Monday. He hopes Jamaica’s Olympic athletes, who he says share the same exuberant defiance of the island’s musicians, will be able to attend. He then has further shows in Spain and Italy.

Globetrotting Jamaican artists, he believes, are travelling ambassadors (“just like you have the tennis circuit”), “spearheading this peace movement through the world”. This process, he says, is “the repatriation of the African spirit.”

During the Garance Festival, a huge reggae extravaganza in France, Andy reflected with his ageing contemporary Fitzroy “Bunny” Simpson, of the group Mighty Diamonds, on how a music that they and their peers began in the Sixties by improvising with instruments fashioned from household items like kitchen pans and “chimmies” (chamber pots) could have achieved such international acclaim. “At my age of 68 I can still participate manfully and enjoy the success of my peers of successive generations. It’s a script I couldn’t really have written for myself,” he says.

He is generous in praise for younger reggae artists such as the “magical” Beres Hammond and the upcoming group Raging Fyah, who clearly identify with Bob Marley & the Wailers. And he rejects the notion that computer-based dancehall reggae has extinguished the fine musicianship for which his generation of Jamaican performers was known. Instead he credits the island’s Edna Manley College of the Visual and Performing Arts for a revival in “musically literate” artists.

But he is clearly not so impressed that some modern reggae artists have given the genre a reputation for intolerance (“All the militancy and misrepresentation and officiousness that came towards certain people with alternative lifestyles”) which is at odds with its essential ethos. “The music’s message is still peace and love and consciousness. More than anything else reggae music represents the consciousness within.”

Andy is writing a biography. It will include details of how he recorded classic songs such as “Too Experienced” (later a huge hit for Barrington Levy) by simply approaching the microphone and singing spontaneously. “The rhythm was there. I just listened to the [music] two or three times and said OK! That’s a tremendous exercise when you go through a five minute explosion like that.” Other great reggae artists such as Delroy Wilson, Leroy Smart and Marcia Griffiths are indebted to Andy for the hit songs he has composed for them.

Rather than bemoan his own lack of recognition, he expresses regret that more credit is not given to his late friend Jackie Mittoo, the great pianist and Studio One musical director. “I think Jackie Mittoo is single-handedly most responsible for the musical quality, styles, arrangements and I have to say creative production [of reggae].”

The composer of songs that railed against social injustice, such as “Life” and “Fire Burning”, Andy has not lost his edge. He is enaged by international current affairs and concerned by the possible motives behind Chinese investment in Africa. He complains of the powers the banking system has exerted over Western economies since the 1930s.  For all his patriotism he would like Jamaica to mark its anniversary with a “forensic audit” of its finances since 1962. “Let’s see how much money came, who spent it, where did it go and did we get value for money?”

He estimates that something like 50% of the early reggae pioneers, including Marley and Mittoo, have passed away. But away from the public gaze, he has been able to find his way to “the most real place I could find”.

After an impoverished upbringing in rural western Jamaica, Andy educated himself. “I never had any schooling so I became a road scholar,” he says, punning on the prestigious Rhodes scholarship offered by the University of Oxford. As he himself wrote in another of his enduring recordings “My Time”: “ Experience has taught me wisdom , thank God I’ve got some life left.”