Concha Buika has a confession to make, one that could irreparably damage flamenco. Preparing to make her British debut at Sadler's Wells theatre in London on March 14, the hottest property the world of traditional Spanish music has seen in many years tells me that she prefers going to bed early over trawling Andalusia's bars caterwauling until dawn. “I live a quiet, healthy life,” she says, “and I only go to flamenco clubs occasionally, when my manager isn't looking.”

The 35-year-old singer tells me this only after I have risked developing cancer through passive smoking in La Carboneria, Seville's most notorious late-night flamenco bar. If you've ever felt short-changed after a show packaged up for tourists on the costas, this is the antidote. It is 3am and, accompanied only by an acoustic guitar, a middle-aged woman with dyed orange hair and an elaborate white dress is stomping around a tiny stage entertaining a crowd of students with tales of a life in which she has been dealt just one bad hand too many.

This is where musicians come to wind down after shows, and where a knowledgeable crowd waits to be entertained. The wisdom of the cognoscenti is perhaps all La Carboneria shares with Sadler's Wells, home to an annual two-week flamenco season that begins on March 3. For one thing, the air is so thick with cigarette smoke the staff should hand out oxygen tanks at the front door. This, undoubtedly, is the real thing.

Brought up in Palma de Majorca, Buika is used to being the healthy odd one out among the flamenco crowd. The most obvious reason for this is that her roots lie not in the Gypsy communities but Equatorial Guinea, and though she grew up near a Gypsy area she is dubious that there was any kind of affinity between those traditional outsiders and her family, the only Africans on the island. “There were things we had in common, but it was coincidence, not the reason we were living next to each other. Maybe life was hard for us, but growing up is difficult anyway and I don't know if it was really any harder for me than anybody else.”

In London, her small band will create an intimate atmosphere in contrast to the flash and acrobatics of the dance companies of Los Farruco (Mar 7-9) and Rafaela Carrasco (Mar 15); while her voice, influenced by American jazz vocalists, provides different flavours than those of purist flamenco singers such as Carmen Linares (Mar 10).

Her singing career began at 17, when somebody offered her aunt 10,000 pesetas to perform at a blues club. The aunt said no but the niece volunteered, despite having being kicked out of the school choir. More dates followed and her reputation grew. Her pre-flamenco CV includes a clutch of appearances on dance singles and a stint in Las Vegas, where she sang in casinos and impersonated Tina Turner and various Supremes. She even recorded an album that disappeared without trace.

Her self-titled debut was definitely African and Spanish, but it owed too much to contemporary American soul to stand out from the crowd. A year later, however, Mi Niña Lola did just that, becoming a benchmark of new flamenco. Though still influenced by soul and jazz, her voice had turned throaty and rough, filled with an intensity that comes from deep within. Her third album, due in April, confirms this was no one-off.

“It's better to sing about a hard life than live one,” she says, clearly differentiating herself from other flamenco and jazz singers. “I could tell the stories of Billie Holiday or Ella Fitzgerald, but they sang the truth about their lives and I wouldn't want to live like them. I don't see myself in Amy Winehouse.” Though it is easy to equate flamenco with clichés about hardship and passion, Buika makes you believe in the truth within those clichés. Her guitarist, Niño Josele, is accompanied by a battery of palmas (clapping) straight from every campfire scene you have ever seen, from Carmen to From Russia With Love.

Though far too modest to present herself as a spearhead such as the Andalusian singer Camaron de la Isla, who dragged flamenco out of the gaudy music halls and turned it into a dynamic modern musical force in the 1970s, that is the position in which Buika finds herself. There is a mood of optimism that she has picked up on, in a way that the fado singer Mariza has with another Latin musical form that had fallen into disrepute.

“It's more than a style of music,” she says. “It exists in everything. Flamenco is the universal music in Spain, and once people have taken it in, it leaves everyone in the same place, it's a unifying music. Within it you can play soul, you can play blues, you can play jazz.”

And this experience extends farther than Spain and the Spanish diaspora. Buika has already played flamenco festivals in Spain, Italy, Colombia, New York, Mexico and France, and now she is looking forward to London. “All these people gathering to share feelings. I didn't seek out this special position, and now I have a great responsibility.”

If sharing the same festival bill as flamenco legends such as Linares scares her, she doesn't show it. It's a sign of rude health for the genre, a positive indication of the future. But one thing is certain: if you want to see Buika at her best, be sure to turn up on time. It's curtain up at 7.30pm, and she likes an early night.

Flamenco Festival, Sadler's Wells, London EC1 (www.sadlerswells.com 0844 4124300), today until Mar 16

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