Beth Orton, Royal Albert Hall, London

It's a safe bet that Frank Sinatra didn't begin his debut Royal Albert Hall performance with a string of four-letter words, but then the folk siren Beth Orton is a self-confessed potty mouth, and as she tells us excitedly, tonight's gig is a celebration. It marks the first anniversary of Daybreaker, her third and current LP, as well as the end of a worldwide tour. It's now four years since the release of her Brit award-winning, breakthrough second album, Central Reservation, and though Orton is perhaps no longer at the height of her popularity, her biggest show to date is a sell-out.

Despite the expletives (she swears a lot), Orton rises to the occasion. Her four-strong band, (referred to as the Good Eggs, you know, like Nick Cave's Bad Seeds) and eight-piece string orchestra fill a stage draped with fairy-lights that tumble from a womb-red back-drop like glittering ivy. Orton herself is dressed in a neon-patterned mini-dress that Twiggy would've loved and – we're assured – rarely worn three-inch stilettos. Fortunately, her aching feet don't interfere with her performance.

Fears that her delicate sound would be lost in the enormous space are forgotten right from the start of this epic 19-song set. The hall's acoustics lend Orton's reedy voice a glacially fragile majesty – absent on her records – that helps it leap effortlessly from coy whisper to full, bold soar. The sound of the band, too, is opulent without being overpowering: furious Celtic strings swell and subside like timelapse-filmed photosensitive flowers. Even beautifully understated moments, such as the gently shuffling guitar on "Ted's Waltz", fill the hall. With some songs the musicians find a deeper, truer expression than their studio incarnations. For example, the crowd-pleaser "Sweetest Decline" loses its lounge-jazz feel in favour of orchestral surges so sweet you wish you could smell them.

But despite the lush surroundings and amazing sound, tonight's pièce de résistance is Orton herself. Mouthing off like the proverbial sailor, she charms the house with her self-effacing wit and just-off-down-the-Queen-Vic cockney humour. She's so obviously thrilled to be playing the Albert Hall that, in a refreshingly uncool move, she has her picture taken in front of the crowd. At the end, less than a minute after her encore, she emerges again apologising: "I don't come here often, you know." Not wanting to leave the stage, she plays a little while longer. And not wanting her to stop, we stay and listen.