THOUGH the National Youth Choir of Scotland - more than 80 singers between the ages of 16 and 24 - is almost three years old, I'm ashamed to say that, until Monday's opening concert of their present short tour, I hadn't heard them in the flesh.

The experience, especially in the magnificent acoustic of Stirling's great Holy Rude Church, was breathtaking. It's not just that they are a good, strong, extremely well-disciplined and organised singing force - drawn from throughout the country, individually auditioned, and welded into a homogeneous outfit under the infinitely persuasive direction of their conductor, Christopher Bell, you would expect no less.

But what was genuinely astonishing was the sophistication of the musical performance. (And the fact that it was achieved in just three days of intensive rehearsal made it the more remarkable.) Any fleeting rough edges in attack or timbre will be smoothed out as they sing throughout the week.

Right from the outset they were striking, in the variation in tone colour with which they imbued the opening phrases of Britten's Rejoice in the Lamb. And from that point, the performance was a catalogue of delights: in sonority, expression, articulation, and - perhaps above all - in the sheer variety of polished choral sound.

Fearlessly, they launched into James MacMillan's wondrous Divo Aloysio Sacrum, producing exactly the right sense of a slow cascade of Technicolor sound in this beautiful choral rainbow. And, on another level altogether, the mature, mellow, velvet textures they generated in Durufle's Requiem were not only appropriate to the piece, but extremely touching. Throughout, John Langdon accompanied flawlessly on the kirk's splendid organ, showing it off in all its voluptuousness in Frank Bridge's Adagio. Superb concert. Same show tomorrow, Caird Hall, Dundee.