THE longest night (Lussinatten) is celebrated in Scandinavia on December 13 in accordance with the old Julian calendar, merging Christian and pagan traditions through the light-bearing figures of St Lucia and Lucifer. It has spawned a huge body of folksong, which fits neatly into the early – and earliest – music in this seasonal festival.

The Society of Strange & Ancient Instruments (SSAI) is ideally placed to revive this material. This deft threesome plays eclectic instruments: a Hardanger fiddle (Benedicte Maurseth, who also sings); a clàrsach or gut-stringed Celtic harp (Jean Kelly); and a nyckelharpa or keyed fiddle (Clare Salaman). They concentrated on Norwegian and Irish traditions with a seasoning of English thrown in. Importantly, they used no printed music.

Maurseth’s light soprano was almost a fourth instrument here, her moods distilling the message better than mere language. On her native Hardanger fiddles, she was mesmerizing, helped by their in-built drone. She generated a feeling of distilling the cool, clear water of Norwegian folk. Her own Vals in duet with Salaman was also touchingly folk-hued.

No less authentic were Kelly’s graceful fingers caressing the harp, the hands gently imitating one another in the Wexford carol or improvising rippling accompaniment to voice or fiddle. She provided essential underlay with unfailing delicacy.

Salaman’s easy technique and ready smile were equally endearing. She gradually adapted a troubadour song into an hypnotic Baroque cadenza and generally supplied the meat in the sandwich. A memorable evening, topped off with Irish polkas.