Though Brahms’s Op 120 Sonatas were composed for clarinet and piano, they belong just as firmly to the viola repertoire. In making alternative versions Brahms took considerable trouble in adapting the viola part, adding occasional double stops and fitting the music to the instrument’s generally lower tessitura. It’s rather surprising, then, to find Rachel Roberts, in the first movement of the Second Sonata, reverting in places to the clarinet version, when Brahms has put the viola line down an octave. Lawrence Power demonstrates how fine these passages can sound when played as the composer intended.

However, this is a small matter in the context of some exceptionally beautiful, searching performances. Compared to Power and Simon Crawford-Phillips, Roberts and Lars Vogt adopt more spacious tempi. For example, in the Andante with variations that closes the Second Sonata, their initial speed may seem slightly slow but they do keep the music moving, and when they get to the third variation with its demisemiquavers, the playing is truly grazioso, as marked. Vogt has a wonderful way of making the textures crystal clear without sounding dry, and he produces more subtle and extensive variations of touch and tone than Crawford-Phillips. Roberts and Vogt together demonstrate a command of idiomatic rubato – for instance, in their freely expressive playing of the theme of the First Sonata’s slow movement. And in Rachel Roberts’s hands the viola quite loses its Cinderella image, nowhere more so than in the Märchenbilder; impressively agile in the third piece, wonderfully warm and rich in the closing lullaby.