Championing the double cause of new music and Welshness — both minority attractions, judging by the size of the audience — the BBC National Orchestra of Wales opened last night’s Prom with a commission by Guto Puw (b.1971), inspired by a tale of men of Harlech, battles and feasting from the Mabinogion.

The work’s first hurdle is its title: ... onyt agoraf y drws...(unless I open the door ...). Repeat that with your eyes shut. Yet the work is wellcrafted and vivid, exploiting the Albert Hall’s spatial possibilities with soloists dispersed on high, notably a fanfaring trumpet.

First impression is of a work driven by illustrative, filmic tendency. A second hearing may reveal more enduring qualities. Walton wrote his Viola Concerto early in his career (1928-9), later reducing the orchestration to allow the subtle and dusky toned solo instrument every chance to shine.

This was the edition played here, superbly, by awrence Power, at his most eloquent in those passages of rhapsody and poetic reverie. The orchestra, conducted by David Atherton, provided sensitive accompaniment. Then Atherton steered an assured, at times glittering account of Rachmaninov’s Symphonic Dances, with melancholic solo woodwind.

But the strings, some of whom look sleepy, tended towards the insipid. The violins could learn from their leader, Lesley Hatfield. She operates from an entirely different energy base which, if emulated, could double their richness of sound and make a merely decent performance electric.