Joanna Newsom's popularity should make us optimistic about the survival of real, if eccentric, creativity. That a shrill-voiced harpist who has released a triple album of chorus-free songs about the 19th-century courtesan Lola Montez should sell out two nights at a 3,000-capacity venue is cause for hope. That Newsom should take these arcane elements and present them in a way that isn't precious is a real feat.

Taking centre stage behind an enormous harp, with her flowing locks and floor-length gown, Newsom came across like a pre-Raphaelite muse, until she opened her mouth. Referring to the audience as "you guys", she broke the spell: here was a modern Nevada City girl. She has matured, too: the affected caterwaul on her 2004 debut, The Milk-Eyed Mender, has been replaced by a softer, more natural timbre. Newsom claims this is due to an operation on her vocal cords; it could also be due to her growing confidence.

At the heart of her music is a melodic sensibility in the classic American tradition. She moved to piano for a languid love song called Easy, which, with its rolling melody and lyrics about cutting yourself off from the world with a lover, was closer to Crosby, Stills and Nash than the fairy folklore she's usually associated with. Even the 11-minute title track of her new album, Have One on Me, proved far more robust than her image suggests.

As Newsom took breaks to tune up, her band fielded atmosphere-smashing questions from mischievous audience members. "What do you think about the pedestrianisation of Norwich city centre?" asked one, before Newsom got things going again with a lament called Ribbon Bows. A standing ovation and an encore of the wistful Baby Birch completed an evening that, though magical, was most resolutely not away with the fairies.