The choir, generally known simply as NYCOS, exists independently of the National Youth Orchestra of Scotland and since its inception has been under the direction of Christopher Bell. He is also the chorusmaster of the Royal Scottish National Orchestra Chorus, a position he has held since 1989, and was appointed music director of the new Ulster Youth Choir last year. He will take NYCOS to perform in concerts in Belfast and Dublin in early September.

Those concerts will follow hard on the heels of a prestigious appearance in Edinburgh, when the choir will perform at the UK premiere of the full orchestral version of American composer Morten Lauridsen’s Lux Aeterna at St Mary’s Cathedral on August 29 and 31, with the Scottish Chamber Orchestra.

Its concerts in Stirling and Aberdeen last week gave a preview of that work. It provided the culmination of an impressive evening in which the choir performed a challenging repertoire with considerable distinction.

The complexities of the music stretched and occasionally exposed the singers, but it was readily apparent that a lot of hard work had taken place in the week-long summer school which preceded the concerts.

I heard the second of them, at the MitchellHall in Aberdeen, which featured a selection of short works sung by the training choir, under the direction of David Lawrence. Although a little less demanding, these - sacred works by Faure and Britten, a folk song, and lighter settings by Ronald Cork and Howard Goodall - were performed in accomplished fashion by the smaller group, with a pleasingly homogeneous ensemble sound.

The main choir also achieved a generally good balance and blend of voices, although the opening work, Benjamin Britten’s Hymn to St Cecilia, was a little tentative in places. The uncredited soloists did very well, both here and in Michael Tippet’s Five Spirituals from a Child of Our Time, which closed the first half in agreeable fashion. In between, they dispatched Herbert Howell’s Take Him, Earth, for Cherishing in poised fashion.

The second half opened with the choir singing John Tavener’s Funeral Ikos from the adjoining room, a distancing effect which Tavener likes to employ. The lovely melodic line of his music floated through the curtains in beguiling fashion.

Lauridsen’s music in Lux Aeterna shared a basic simplicity of approach with the Tavener piece, albeit with a more undulating line and more dramatic unison intervals. The singers again rose to the challenge in impressive fashion, both in their technical control of the music, and in their grasp of its expressive demands.