This was a bold venture, even by Unthanks standards. They have considerable experience playing concert halls, but presenting an acoustic show at the mostly unseated Roundhouse, a former engine shed, would still be a challenge. Especially as they were concentrating on new songs from Mount the Air, an album of gentle melancholia that features lengthy instrumental passages.

They succeeded by reworking the album, mixing jollity and variety with the softly bleak songs. It was a shrewd move to invite that rousing a cappella trio the Young’uns to open the show, transforming the Roundhouse into a large, cheerful folk club.

The Unthanks followed with a performance that cleverly shifted between their folk roots and their elaborate excursions into art folk. The two Unthank sisters, Rachel and Becky, were centre stage, starting with a languid and exquisite treatment of Charles Causley’s poem Hawthorn. They were surrounded by pianist Adrian McNally (who dominates the album), a string quartet, along with double bass and drums. Fine classical trumpeter Victoria Rule, who has worked with Elbow, produced drifting, jazz-influenced solo work on Mount the Air’s title track before the sisters transformed it into an cheerful clog dance.

They switched from the sturdy misery of Died for Love to spine-tingling harmony work on Magpie, accompanied by their violinist Niopha Keeegan. By the end, they had switched to songs by King Crimson, Antony and the Johnsons, and Robert Wyatt and Alfie Benge, with the strings providing an edgy backing to Wyatt’s Out of the Blue. They ended a cool and triumphant set with a return to the new album, and clog dancing.

• At the Leeds Irish Centre on 10 March. Then touring Ireland and the UK until 20 March.