One of the joys of being a music critic is that every so often you come across a totally unexpected gem — and last Sunday, at the Holywell, acoustic folk group Spiro turned out to be just that. The Bristol-based foursome have grabbed themselves a unique place in the folk music scene, with a refreshingly different sound that eschews vocals and solo instruments in favour of solid ensemble playing. The four instruments — violin/viola (Jane Harbour), guitar (Jon Hunt), mandolin (Alex Vann) and accordion (Jason Sparkes) — gyrate around each other in a harmonious fusion of styles, in which traditional English folk meets modern classicism and electronic dance music. The result is a well-crafted, resolute sound that is richly-textured, strong on rhythm and melody, and utterly compelling.

Most of Sunday’s gig drew on the band’s recent, highly-acclaimed album, Lightbox, which was released on Peter Gabriel’s RealWorld label and helped catapult the band from obscurity to the recognition they surely deserve. Much of Spiro’s music is inspired by traditional melodies from Northern England and the Scottish borders, such as Shaft, a bright, energetic piece based on a Northumbrian pipe version of Bobby Shaftoe, Pop (Highland Laddie) and The Radio Sky (The Bonny Pit Lad) and these, for me, were the highlights. There was also the evocative I Fear You Just as I Fear Ghosts, with its haunting melancholy, and a new, as yet untitled piece, which the band only finished composing last Friday, and which is surely destined for their next album.

Supporting Spiro was hurdy-gurdy player Cliff Stapleton, whose two improvisations offered a rare opportunity to hear this now little-used instrument. This was fascinating stuff, but the evening, indisputably, belonged to Spiro, whose imaginative, experimental sound, underpinned by virtuosic playing from all four members of the band, was mesmerizing. Absolutely sublime. You can catch the band in Chipping Norton on June 12 — www.chippingnortontheatre.com for details.