I kept having to pinch myself: the sounds coming from the stage were not in fact from the CBSO, but from the CBSO Youth Orchestra, playing with a maturity of delivery worthy of the mentors who had guided these youngsters through a week of intensive training.

And their performance was a well-deserved reward for Michael Seal, who had presided over the whole week and who on Sunday evening drew immense riches from these players in what I consider his greatest conducting triumph yet, since he vacated his desk among the CBSO second violins.

Horns were a little over-awed at the beginning of Nielsen's Helios Overture (perhaps not fair to put this tepid sunrise-to-sunset piece in the same programme as the masterpiece which was to follow), but it progressed with seamless narrative lines, eloquent oboe solos, chattering woodwind detail, and a well-balanced, busy fugue.

The Scandinavian theme continued with Magnus Lindberg's Clarinet Concerto (at last a worthy addition to a depleted repertoire), its sounds for both orchestra and soloist (successfully exploratory) well-imagined, and always conveying a convincing argument over its 25-minute span.

Julian Bliss was the assured soloist, fully up to the work's demands of phrasing, breathing, and embouchure-technique. Gloopy microtones, comedic effects? No problem, and always unfolded in a logical line teeming with incident. Seal's CBSOYO collaborated with an empathy which belied their years.

Finally came the awesome challenge of Richard Strauss's Alpensinfonie, a dawn to dusk traversal of a Bavarian mountain, and totally moving and exciting in its performance here. Winds are often easy to praise, and these deserved to be, but not so often do we mention the strings; here they were extraordinary, pouring out a wonderful maturity of tone, not least from the lower cohorts.

I cannot praise enough the maturity of every section. I have heard young brass players showing off like nobody's business. I have seen percussionists turning what they do into a theatrical performance.

Nothing like that here. This was an Alpensinfonie under Michael Seal which was all about the music, and it will stay long in the memory.