Buenas noches Buena Vista

The pair are part of the diminishing band of venerable Cuban musicians who gathered in Havana in 1996, under the auspices of Ry Cooder and Nick Gold from World Circuit records, to create a landmark album. Buena Vista Social Club went on to sell over eight million copies, in the process dragging Cuban 'son' music out of its world music niche and into kitchens, cafes and concert halls around the globe.

Featuring Portuondo and Ochoa alongside local legends such as Ruben Gonzalez, Ibrahim Ferrer and Juan Macros de Gonzalez, the album was recorded in March 1996 and released the following year. In 1998 the musicians staged a triumphant concert at Carnegie Hall (New York, not Dunfermline), and in 1999 came the award-winning documentary film, directed by Wim Wenders. Though the majority of the original musicians - many of whom were already of a somewhat advanced vintage when the album was recorded - are now dead, the venture has been kept alive by the Orquestra Buena Vista Social Club, a touring ensemble featuring Portuondo and Ochoa alongside original members such as trumpeter Guajiro Mirabal and laúd virtuoso Barbarito Torres.

It has been an incredible success story spun over two decades, but the curtain is about to fall. Last month Buena Vista Social Club released Lost & Found, an album of offcuts from the original Havana sessions, as well as live tracks and related recordings. It includes Portuondo's stirring rendition of Lagrimas Negras, one of the best-loved songs in the Cuban repertoire, and two moving solo performances from Ochoa, recorded late one night when the bustling studio had finally emptied.

Hot on the Cuban heels of Lost & Found comes the self-explanatory Adios Tour, although Portuondo, for one, seems to be in denial that this is indeed the end. ""No, no!" she cries. "I would love it to continue. It's such a sensitive and beautiful project."

Portuondo is a Cuban legend, whose singing career stretches back to the late 1940s. She performed with Nat 'King' Cole in 1953 and hosted her own TV series in the 70s and 80s. Speaking through a translator, she cuts a grand and slightly formidable dash, but softens when recalling those "crazy" seven days of recording 19 years ago. It turns out she almost didn't make it at all.

"I always had a solo career, and when Juan de Marcos [Gonzalez] asked me to come to the studio I was just about to leave to go on tour," she recalls. "Juan de Marcos always had a mission to work with Cuban 'son', and I had that mission too, to promote it and work with it, so I wanted to be there. It was funny. The studio was full of people - we all said, 'who's coming next, who's coming next?' - but I knew it was going to be great. I had an instinct it would be successful, because I always considered Cuban music a treasure. It makes people laugh and dance and cry. It's a music everyone recognises."

"When we were making the record we did it with the full knowledge that it had to be really good," adds Ochoa, plump and pleasant in his cowboy hat and black shirt. "This was our music and we knew it was going to go out into the world. We wanted it to be the best it could be, because we knew it would be there to stay."

For the guitarist, the stand-out memory of this 20-year adventure was the Carnegie Hall concert in 1998. "I was really impressed with the way people welcomed the music, and us," he says. "I could see tears of happiness, not sadness, in their eyes. It gave me the feeling, Well, I'm still good for something!"

The experience has been a game-changer for both musicians, but do they ever feel Buena Vista Social Club has overshadowed the rest of their careers? "No, Chico," smiles Portuondo. "I was able to do my solo career and Buena Vista, so they helped each other." Ochoa agrees. "Instead of taking away from our careers, it has added. Buena Vista took Cuban music everywhere, and that helped me. I've been able to continue with my group Cuarteto Patria, I've also worked on the Afro-Cubism project with Toumani Diabate. The fact that it became so world famous and Cuban music has become so well known throughout the world has definitely been good for me."

The plaudits rained down from all corners of the globe, but what about Cuba itself? While Portuondo maintains that "Buena Vista Social Club has been well received at home," Ochoa is less certain. "For me, it wasn't given, and still isn't, the same amount of attention, publicity and promotion in Cuba as it has had abroad." He looks momentarily pained. "What happened with Buena Vista Social Club hasn't happened with any other Cuban group or artist." That much is certainly true. It deserves a send-off as memorable as its arrival.

Lost & Found is out now on World Circuit. Orquestra Buena Vista Social Club play Glasgow Royal Concert Hall on April 10.