Mulatu Astatke is wearing white plastic bags on his feet and talking to me about sixth-century Ethiopian Coptic Church music. His softly spoken words, barely audible over the loud electro thud of a Swedish house combo performing on a nearby stage, are explaining the concept behind "The Yared Opera", a new oeuvre based on the chants of St Yared, the founder of Ethiopian church music.
"Back then they used to conduct their choirs with a stick," he tells me with weary, yet obliging, nonchalance. "Nowhere else in the world was there a symphony orchestra that was conducted with a stick in the sixth century. The opera is about the contribution of Ethiopian music to the world. That's what I'm defending."
Thankfully, the white plastic footwear isn't a sign of incipient senility but rather an improvised protection against the infamous Glastonbury mud that has smeared itself on every visible surface following last night's heavy, quasi-obligatory, downpour. Astatke seems unfazed by these raw, rock'n'roll surroundings. His presence at the Glastonbury festival, the largest three-day music event in the world, is a source of gentle pride. "I studied, I worked so hard and I created this music called Ethio jazz," he asserts. "Now young people play it all over the world. You know, it's so great to see all this while I'm still alive."
Astatke has the self-confident air of an innovator who has survived to reap rewards and enjoy the golden glow of his slow-burn success. His grafting of the pentatonic scale of traditional Ethiopian music on to the 12-tone structures of western jazz back in the 1960s now has the aura of a quasi-scientific breakthrough. Indeed, Astatke sees himself, and all musicians, as scientists of sorts. "Music is a science," is the claim he makes in almost every interview. "They mix chemicals and we mix sounds."
Perhaps this habit of placing music on a scientific pedestal is Astatke's way of justifying his decision to ditch a career in aeronautical engineering in favour of music. He was born 68 years ago into a wealthy family in the Ethiopian town of Jimma. His father hoped he would pursue a career in something "useful", such as engineering or medicine, but made the mistake of sending his teenage son to a boarding school in the wet and windy wilds of north-west Wales, where music and art were part of the general curriculum. "I think that's the place where I found myself and became a musician," he says.
The next 10 years of Astatke's life would make a good blueprint for the new jazz musical version of O Lucky Man!. He received a formal music education at Trinity College in London and then Berklee College in Boston, where he was the first "black" African alumnus. "Is jazz really something that can be taught?" I ask, somewhat provocatively. "Well, you know," - Astatke prefaces many of his answers with a lengthy high-pitched "Weeeellll!" and a nonchalant shrug of the shoulders - "if you want to be progressive and teach what you know to other people, you have to be educated. In most third-world countries, we need educated musicians. But I love the bush people in my country, the people who created us, all those notes, all those instruments. In fact there are tribes who play a diminished scale of 12-tone music. How they created it, God knows."
Astatke's informal education was even more enviable. He saw, heard, hung out and occasionally jammed with an A-Z of 1960s jazz greats, starting off in London with Tubby Hayes, Ronnie Scott, Joe Harriot and Fela Kuti and following on in New York with Bud Powell, John Coltrane, Miles Davis and the vibes player Dave Pike, to name but a few. He also went salsa dancing to the beat of Tito Puente's band down at the Palladium and it was mainly with Puerto Rican musicians that he formed his revolutionary Ethiopian Quintet and recorded the seminal LPs Afro-Latin Soul Vols 1 & 2, which, together with the 1972 album Astatke of Ethiopia, define the Ethio-jazz genre.
Those were radical times. Jazz and soul music were being ripped apart and realigned to serenade the birth of independent nations. African musicians such as Fela Kuti and Hugh Masekela were busy giving Africa back its musical pride. "I kept thinking 'where's the Ethiopian music?'" Astatke remembers. "I had to come up with something." Those three Ethio-jazz albums became keenly hunted rarities among the cool crate-diggin' jazz DJs of the 1980s and 1990s, and that cult interest kept Astatke's international reputation alive during Ethiopian music's "lost weekend", which began with Haile Selassie's overthrow in 1974 and ended with the release of the first Ethiopiques reissue in 1998.
Astatke returned to Ethiopia in 1968 to find the capital Addis Ababa in full swing, revelling in the dizzy freedoms that resulted from Selassie's loosening grip on power. He became a producer, arranger and general in-house musical "brain" of Amha Records, the label at the heart of the swinging Addis music scene whose catalogue forms the bedrock of the Ethiopiques series. Astatke's taste for improvisation and strange western instruments, such as the Fender Rhodes keyboard, vibraphone or wah-wah pedal, created ripples of protest and dissent among his fellow Addis musicians. But he delighted in being his own man and always has done.
"I always wanted to be different," he tells me. "I had a fantastic tutor at Berklee who always used to say to us every morning 'be yourself all the time'. The art of improvisation didn't exist in Ethiopia at the time. It took a while, but I never stop. Just keep fighting."
When the communist Derg regime took power in 1974 and snuffed out the dazzling hedonism of the previous decade almost overnight, Astatke kept his head down and his music apolitical. "My jazz had nothing to fear. It was instrumental. It didn't have lyrics about this or that. I've never had any problem with any government." Now, thanks to the Ethiopiques reissue CD series, Jim Jarmusch's film Broken Flowers, whose soundtrack features seven pieces by Astatke, and endless tours by Astatke and other stars of the golden age, the lost weekend is over and Ethiopian music is back in the limelight, basking in renewed optimism. As Astatke says, he's lucky to be alive in this new dawn. In many ways he's led a blessed life, with his wealthy parents, his ringside seat during one of jazz's most creative and vibrant periods, his professorial globe-trotting, his field work with Ethiopian "bushmen", and his central role in Ethiopia's time of musical glory.
What about the future? "I think it's really beautiful, really great," he answers. "More international musicians are coming to Ethiopia, more schools are opening, more clubs with youth people. I think it's a nice big future." A few hours after our interview, dressed from head to toe in resplendent spotless white, Astatke takes up position behind his vibraphone and faces the mud-spattered Glastonbury hordes. Around him, the Heliocentrics play his music with a passionate, nuanced simplicity that does it rare justice, while warm notes spill from his sticks and drift off like calm African spirits through the damp English air.