Under the auspices of the Swansea festival, the BBC National Orchestra of Wales marked the 50th anniversary of the Aberfan disaster – when a slag heap in a mining village in south Wales collapsed on a school, killing 144 – with a commission from the young Welsh composer Joseph Davies. The Shortest Day, for soprano and orchestra, set a sequence of three poems specially written by Dr Rowan Williams, in which an observer, standing outside time, sees the tragic events unfold yet is powerless to affect the outcome and even less the suffering. The words evoked that October day at Aberfan and, as soberingly, the catastrophes of the present.

Davies’s handling of the orchestra showed great assurance, adopting the scoring of Mahler’s Kindertotenlieder – plus extra metallic percussion – and finding an expressive balance between the horrific nature of the event and a tender reflection on the innocence of the lost children. At the end of the second poem, Prayer, where Williams fashions a moment intimating the approach of quiet, consoling sleep, the vocal line was beautifully judged. In such passages, the clarity of Davies’s intent and the control of his means were manifest. However, Fflur Wyn’s soprano was sometimes lost in the orchestral flow, an all-too-metaphoric engulfing of her sound, denying the work its ultimate impact.

Wyn and baritone Neal Davies were the soloists in Fauré’s Requiem, with conductor Siân Edwards ensuring that, in the Libera Me, the words “Quando coeli movendi sunt et terra” – when heaven and earth are shaken – were sung with an unexpectedly poignant force by the BBC National Chorus of Wales.

• The Swansea festival continues until 15 October. Box office: 01792 475715.