A cache of manuscripts that had lain forgotten for 300 years was behind one of classical music’s most unlikely pairings: two musicians from opposite sides of the world and from utterly different cultures. Henry Villca grew up in a poor village in Bolivia and earned a living singing in a Mexican folk band. Ashley Solomon studied at the Royal Academy of Music and is a leading exponent of Baroque music as artistic director of the ensemble Florilegium.

The archives of Bolivian Baroque music, composed by European Jesuits and by indigenous people, were discovered by Piotr Nawot, a Polish priest who was director of the La Paz choir in which Villca sang. The manuscripts had been hidden away for centuries in mission churches. Some of the pieces have text in native Bolivian languages.

When he heard Solomon’s ensemble, Florilegium, Nawot decided they would be the perfect interpreters of the music and approached them. He offered Solomon first refusal on a vast archive of unknown music from the period. “I said yes, and Piotr sent me 30kg of manuscripts in the post,” Solomon says.

The first time Florilegium performed some of the music in its native country, Solomon was deeply moved by the audience response. “The audience began singing one piece with us. We can play The Four Seasons every night in London — no one will ever join in.

“The music doesn’t compare in quality to, say, Bach, but it is enormously rewarding. We were all affected by the enthusiasm for music.”

This led Solomon to organise fundraising concerts in the UK for Bolivian children. The concerts were so popular that he decided to record a CD of some of the rediscovered music and to use Bolivian singers to bring out its particular characteristics.

London audiences will have a chance to judge for themselves when Florilegium perform a selection of the rediscovered music, with Bolivian soloists including Henry Villca, at St James’s Church, Piccadilly, on June 15.

Solomon says that the music has the rhythms of Bolivia. “It’s very dance-like and rustic. It has a naivety, like the architecture of the simple wooden mission churches.” The Bolivian voices enhance this with a sound that is “darker, almost dirtier” than that of European singers. “It’s more rustic, not refined like a choir from Cambridge.”

He and Nawot organised open auditions in the Bolivian city of Santa Cruz, and Nawot encouraged Villca to try out. “I was completely nervous,” Villca says. “It was the first time I had ever been in a hotel. I didn’t really know who Ashley was.”

Villca, now 27, comes from the Aymaren community, one of the two indigenous ethnic groups that make up 70 per cent of Bolivia’s population. He spent his childhood in the little town of Viacha, 40km (25 miles) from La Paz. “I never thought of being a musician,” he says. “I thought about going into the military, like my father.” But in his last year of high school he won a place at the conservatoire in La Paz. “I wanted to play my folk music, the pan pipes,” he explains. “But they only taught classical music. I had never heard an orchestra.”

Teachers encouraged him to take up the guitar and he went on to win a national competition. “My father said not to think of a career in music. He thought I would not be able to survive.” Villca struggled to carry on as a classical guitarist, but could not earn a living. “It is difficult to be a musician in Bolivia. The first necessity is healthcare and education. Art is not a priority.”

Folk music drew him back. He joined a choir at the conservatoire and discovered a talent for singing. He began to sing with a mariachi (Mexican folk music) band. “The first concert I did, the people clapped and stood up. It gave me confidence.”

When Solomon heard Villca’s voice at an audition, he could tell immediately that the young man had great potential. “He had a very rich, fruity sound and there was passion and desire in his eyes,” he recalls. “He had raw talent. I thought, ‘If this guy is this good now, after training he could be extraordinary’.”

Solomon selected Villca and three young women soloists, who were all involved in formal music study already, so Villca had to catch up fast. Solomon arranged for him to have singing lessons.

Performing was very emotional for him. “The first day of rehearsals with Florilegium was like a dream coming true.” The soloists performed with Florilegium in Europe’s top classical music venues and were even given a standing ovation at the Konzerthaus in Vienna. Their first CD, Bolivian Baroque, was released in 2005. The project gave all four soloists a boost to their careers, but for Villca it was life-changing. He is now studying at the Conservatoire in Amsterdam. “I would like to sing all over the world and for the public in Europe to know this Bolivian music. Baroque music is the air that I breathe. For me it is everything.”

Florilegium play at St James, Piccadilly, London, on June 15 (020-7381 0441). The second Bolivian Baroque CD will be released on Channel Classics in November.