Lambchop, Union Chapel, London

Lambchop once played so quietly at London's Somerset House that you could hear the birds in the trees above them.

Since the relatively popular peak of their twisted country-soul album Nixon (2000), their records too have become murmuring, interior things. It sounded as if Lambchop's leader, Kurt Wagner, was slowly turning down his loose Nashville collective, till you could hardly hear them at all. But the strong, mysterious songs on 10th album OH (Ohio) are his best since Nixon. Lambchop play them all to a reverent crowd in this north London church.

The band's Nashville roots have always been awkward. It sounds like they're playing the sort of licks Dylan patented in Nashville, even before they resolve into his "You're a Big Girl Now". And steel guitars make many other songs sound like they must be country. But compared with that music's conservative musical formulas, they might as well be science fiction. Most songs have a smooth bullet-train drive, with a shuffling beat on the cymbals and a slow thump on the drums. "Close Up and Personal", meanwhile, could be a dreamy 1950s Nelson Riddle-scored ballad, if it wasn't for the non sequiturs on beer, TV dinners and divine revelation shivering from Wagner's mouth.

Wagner chokes off words and elides sentences, on lyrics which are opaque and encrypted anyway. "I'm a bad enunciator," he says as he sings "A Hold of You". And yet that song's explicit lustfulness is openly sung. His current seven-piece band sink back so you notice him hacking at his guitar, and braying like a werewolf at the moon. He is lost in a sexual reverie that could be for a groupie, but finally turns for home. As with another love song, "Slipped, Dissolved and Loosed", the raw romanticism in his voice, and the music's soft, complicated beauty, could be country.

For all their jazzy stretches and great proficiency, Lambchop's current sound is too consistent, until a shock: dance act X-Press 2's "Give It". Grandiloquent keyboard chords lead to him snapping and pointing his fingers and barking like a gospel preacher, or transported soul singer. "Give me hits," was his half-joking instruction as the band convened for OH (Ohio). Playing with this rocking attack, they could have them. After a pass through old favourites, this perfectly judged gig finishes with Don Williams's "I Believe in You". Wagner, quietly moved that these fans are still here for him, sings its disarmingly kind corn with conviction. Its emotional connection to the warm heart of his own secretive, allusive work is very clear.