Beth Orton, Union Chapel, London

"Call me the sea/ Call me the stream/ Call me the sky/ Call me the leaves," Beth Orton informs us, in her distinctive nasally folk twang, on new track "Call Me the Breeze". There’s a great deal about the elements - the moon, the sun, the sky, the leaves, the breeze, the wind – in this patchy, mainly solo performance in these reverential environs.

The playful and pastoral "Call Me the Breeze" is a highlight tonight among a sea of apologies and minor technical hitches. "Mind if I start again?" she asks us halfway through her first number, "Magpie", before apologising for being "a diva" and duly starting again. There's a lot of this from the self-deprecating singer, who admits "I don't know why I'm so nervous tonight". She needn't be, as she's among ardent "friends", and her tranquil new album (her first in six years), Sugaring Season, is arguably her strongest yet.

At her finest, the former “comedown queen” recalls, vocally and lyrically, the likes of Julianne Regan, Carly Simon, Edie Brickell and Sandy Denny. However, it would have been a slight relief if, just occasionally, the endearing singer had truly let rip (with some gospel, rap, reggae, anything), if only to warm our chilly toes, but there are still moments of transcendental loveliness here.

The pick of her delicate material is the soulful “Something More Beautiful”, on which the willowy 41-year-old sings “When you feel too much to ever let it show/ You turn it up, turn it down, turn it round, and leave/ When you just don’t concede/ With what you believe.” This sensual song would have suited Otis Reading’s voice beautifully.

It's noticeable how much Orton's guitar work has improved under the tutelage of Pentangle founder Bert Jansch, although she unnecessarily informs us of "a guitar malfunction" after the wonderful, Weimar Republic -era sounding "Sea Through Blue". Stop saying sorry.

The new material stands up extremely well against tracks from her first two critically lauded (both were nominated for a Mercury Prize) folktronica albums, Trailer Park and Central Reservation. However, the mournful lament “She Cries Your Name”, her breakthrough song (which memorably includes the word "euphorically"), is still her most compelling track. "Oldies" such as "Central Reservation" and "Shopping Trolley" are also treats.

For the encore Orton exclaims "Anything you want played, just tell me". She's met with sporadic, barked demands, which she awkwardly tries to please.

Orton, with fewer apologies and with a full band, is capable of a barnstorming performance, especially off the back of her exquisite new album. But tonight wasn't quite the night.