When you’ve spent the best part of a week rehearsing a difficult but short piece of music for public performance, it might be worth giving it a double airing.

That was the thinking behind two performances of Tallis’s Spem in Alium in the first half of this concert by the LSC, conducted by its musical director, Simon Halsey.

The popularity of the work, which lasts less than ten minutes, is one of the notable legacies of Classic FM and the promotion of music that without its crusading zeal might never have become widely known.

It’s scored for forty voices (or their multiples, as in this case) in eight blocks of five - separate choral units in fact - and its polychoral complexities are legion. The massed ranks of the LSO chorus resulted in burial of some of the detail but came into their own when united.

With literally forty voices and in a cathedral, it would have been a different experience and a different sound.

The high numbers were present for the hour-long Rachmaninov Vespers, which benefited from the populous but disciplined turnout. Halsey was able to guarantee impressive and slow-moving arcs of sound, anchored by some characteristic bass-singing, though not the kind that reached the low B flats with the legendary resonance of the Russians.

Uncertainty surrounds the provenance of the Tallis work but the possibility that it marked Queen Elizabeth 1’s 40th birthday was an excuse to include two 20th-century Royal commissions from Welsh composers.

Paul Mealor’s brooding Ubi Caritas now makes the earlier Let The People Praise Thee, O God by William Mathias seem unadventurous, even or especially with the latter’s organ accompaniment. But neither would be sung much better than this, with Halsey‘s trademark vitality much in evidence.