The Unthanks – Nottingham Arts Theatre, Thursday October 15.

When they last performed here – at The Maze, in December 2007 – Rachel Unthank and the Winterset were a sparsely arranged quartet, touring in support of a strange and sublime new album (The Bairns) that went on to be nominated for a Mercury Prize. Two years on, with Rachel’s younger sister and co-vocalist Becky promoted to equal billing, The Unthanks have expanded to a ten-strong touring line-up, complete with string section, brass section, keyboards, a banjo, a ukulele, and just about any other instrument you might care to mention. Almost every musician on stage performed in multiple roles. The trumpet player might switch to guitar, or the drummer might grab a double bass. And yet for all the activity on stage, the sound remained spacious, restrained and wonderfully pure.

With their new album (Here’s The Tender Coming), Rachel and Becky have made a conscious decision to move away from “the stark bleakness of The Bairns”, in favour of something “calmer and a little warmer”, as they put it in the sleeve notes. But although the boundary-crossing Robert Wyatt and Will Oldham covers may be gone, the music continues to draw on a wide range of influences.

There were shades of Michael Nyman’s soundtrack music to be found in Lucky Gilchrist: an affectionate tribute to a recently deceased friend (“a bit like Freddie Mercury, camp and yet angry, except you had a lady”) which ended with a spirited display of Northumbrian clog dancing. A cover of Sexy Sadie from the Beatles’ White Album was a surprise addition – as was a re-arrangement of Blackbird from The Bairns, in homage to the Penguin Café Orchestra. The Lancashire street song Where’ve Yer Bin ‘Dick teetered amusingly on the brink of obscenity, while The Testimony Of Patience Kershaw was a raw and riveting setting of a 17 year-old’s actual spoken testament to a Royal Commission on Children’s Employment in 1842. (“I try to be respectable – but Sir, the shame, God save my soul.”)

The slightly down-at-heel gentility of the Arts Theatre – a venue which feels frozen in the 1950s, in the most agreeable way – proved to be a perfect setting for this kind of music, and these kinds of songs. Let’s hope that more concerts of this quality are staged there in the future.