Katia Guerreiro, Purcell Room

One of the unintended results of Mozambican-Portuguese superstar Mariza's sudden fame - unintended, because she reveres the tradition from which she springs - is that fado is now regarded, in Britain at least, as a flamboyant performance art. Fado has always had its stars, and they've often been flamboyant people, but it is essentially about voice, pure and simple, and is best delivered while standing still. It is also generally forgotten that in its Twenties heyday fado was the battleground for two violently opposed factions: those who claimed it as the music of the people, to be sung in taverns, and those who claimed its proper place was the drawing room. In those days, professors wrote fados, and often sang them; the fado lyric has always been the preserve of poets.

If you want evidence of this, you can either listen to the period compilations on the Heritage label, or you can seek out singers less showy than Mariza who preserve the tradition intact. The 26-year-old Katia Guerreiro is one of these: brought up in the Azores, and now a trained doctor, she has somehow also blossomed into a quintessential fadista. Or, rather, bloomed, because her eyes - swooningly closed when she sings - suggest dark flowers. Gorgeous in her spangled robe, she stands at the microphone as though at an altar where she communes with spirits above.

There are two schools of fado - tear-drenched in Lisbon, more cheerful in Coimbra - and I'd say her style evokes the latter, but her artistry goes to the timeless heart of the matter. She never forces the pace with her warm, dark timbre, moving gently in tandem with musicians on Portuguese guitarra, Spanish guitar, and bass. Her effects are perfectly calculated, delivering the first note of a song with the characteristic long-held call, or modulating abruptly from a soft murmur to a full-throated cry. But they manage the trick of seeming to express spontaneous feeling; at climactic moments she drew growls of approval from the Portuguese cognoscenti in the Purcell Room.

Meanwhile, in a church off Lisson Grove - a surprise. Under the direction of their leader Venice Manley, Maspindzeli Choir deliver Georgian songs with enormous panache. Yet there's hardly a Georgian among them: that strife-torn land in the Caucasus has long cast its spell over Britons, of which this group of enthusiasts is proof. "We don't know what the words of that song mean,' says Manley, disarmingly. "But deep down, of course, we do." Shut your eyes and these really are Georgian voices, with the female soloists finding exactly the right hard, bare sound, just as they do in Tbilisi.