Bert Jansch with Beth Orton, Spitz, London

We all get nervous. And when we do we sometimes swear too much and our dexterity is compromised. Things weren't so bad that Beth Orton (pictured) insulted the audience and Bert Jansch broke his guitar on the heads of the front row, but the duo's unease was palpable. Was it the engulfing heat? The press of expectation? Not enough rehearsal? Orton gulped water and cursed several times; Jansch's fingers failed to walk more than once and sounded stiff the rest of the time. Yikes, one felt, shoving one's hands deeper into one's pockets. This is what it's like to be human.

Jansch is about to commence a world tour, while Orton is off to have a baby. "I'm pregnant," she announced brightly, before trailing off: "So mum's the word and all that..." They then entered the most effective passage of their performance, the gawky romanticism of "Watch the Stars" and the elegant blues "My Pocket's Empty" by a second guitarist, Paul Wassif) somehow allowing the assembly to relax a little. They are two of the three songs on Jansch's recent album The Black Swan that feature Orton, which suggests that they may have been played before, more than cursorily.

Things then went wonky again. "This song is bloody lovely," said Orton, gulping. "I love this song, but I'm not sure it loves me." She then murdered what sounded like an old English ballad about underage sex - sharp, flat and most points in between - which turned out to be Pentangle's "The Trees They Grow High", the very height of that group's curious elision of the English folk tradition and art-jazz. "That was hard," Orton gasped afterwards, as applause rippled like the surface of a small pond in a slight breeze. They then tackled Pentangle's "Here My Call". You have to like the woman.

Jansch remained inscrutable throughout, eyes down. His singing observed its usual conventions of extreme diffidence allied to subtle shifts of weight, even as he eased himself in with "Carnival" and "Key to the Highway". "We've enjoyed ourselves," he half-smiled at the end, "despite all the mistakes."