Tall, skinny and handsomely bearded, Alasdair Roberts shyly popped up ahead of schedule, lending his voice to impressive support act Elle Osborne’s final song.

Roberts’s Perthshire brogue is unmistakable, as is his spindly acoustic guitar plucking and fondness for lyrically dense, complex material. “We’re going to do some old ballads, muckle sangs and new songs,” he told the reverent audience.

The other part of the “we” was composer, ensemble director and lecturer David McGuinness. The pair’s differing approaches were complementary, McGuinness adding rich, jazzy piano to Roberts’s spiky guitar and dialect-heavy singing.

Roberts’s own compositions are possessed of a similar poetic spirit to the traditional songs of his homeland, making for a cohesive set – albeit one that required careful listening. Fusion Of Horizons told us “love is a trellis of early roses/a shady arbour the soul encloses” while McGuinness evoked the sound of bagpipes with his melodica on Coral And Tar.

On the traditional side, the duo delivered versions of Babylon and Young Johnson – both bitter stories of crime and death. But their gentler encore – the tragic Trees They Do Grow High – proved they had the warmth and heart to match their thrilling intensity.