Joan As Police Woman, Union Chapel

You’ve got to take the pedal off the metal at some point, and in 2009 the prodigiously energetic New Yorker Joan Wasser – otherwise known as Joan As Police Woman - has apparently decided to ease up and release an album of cover versions.

Any suspicions, however, that this might result in a night of cute karaoke knockabout were dispelled as soon as she took to the stage for an ecstatically received, sold-out show at London’s Union Chapel last night. Having spent the past 15 years working alongside pop auteurs of the calibre of Antony (of the Johnsons), Rufus Wainwright and Jeff Buckley, her partner at the time of his death by drowning in 1997, Wasser is an old hand at subverting expectations. Now on her fourth tour of the UK, she has gathered a devoted following here – as well as a highly supportive British label – who have turned this 39-year-old Brooklynite into a predominantly expat phenomenon.

Last night Wasser played what was, by her diva-ish standards, a low-key set. Her trademark grand piano and electric viola were both absent, as was her band. Compared to the lush and complex arrangements of her last album, To Survive, written in response to her mother’s death from cancer, Cover is a relatively straightforward, unplugged-style collection in the key of alternative rock.

Not that there was anything predictable in her choice of material. Appearing with a single accomplice, guitarist and drummer Timo Ellis, and a four-track mix tape, Wasser performed an idiosyncratic selection of songs that confirmed her reputation as one of the most engrossing mavericks on the East Coast art rock scene. Who else could have invested the Britney Spears’s tune "Overprotected" with such a darkly flippant air before launching into the obscure Iggy Pop/David Bowie opus "Baby", and then offering a radically decelerated, moody version of the Jimi Hendrix classic "Fire"? As she explained that this was her “interpretation domination” tour, it became clear that part of the fun for the audience lay in identifying songs they barely knew, such as "Sacred Trickster" by Kim Gordon of Sonic Youth, and the blatantly erotic come-on, "Whatever You Like".

Technically speaking, the show didn’t run as smoothly as it might have. Wasser’s mini-keyboard acted up from time to time and the sound balance in the boomy hall could seem offputtingly brittle. The strongest sections were those in which her unhurried vocals allowed the songs to breathe, and her easy way with the audience – inviting a woman up on stage at one point to show off a rather fetching Arts and Crafts shirt – induced a sense that this was our show as much as it was hers.

The sense that this performance was an intermission in the upward JAPW career curve was underlined by two beautiful new songs, "Flash" and "Human Condition", neither of which feature on Cover. Joan Wasser is, at root, an artist who, as somebody called Dylan once said, “don’t look back.” She may have teased us with a bit of over-the-shoulder stuff last night – and tremendously entertaining it was too - but the odds are it will be business as usual soon enough.