If it did nothing else, Forkel’s origin story for the Goldberg Variations immortalised the name of Bach’s student, who would otherwise warrant the merest footnote in music history. On the showing of these trio sonatas, he wasn’t the talentless hack portrayed by some of Bach’s early biographers. The introductory essay by Ensemble Diderot’s leader, Johannes Pramsohler, situates his music usefully, untroubled by either the galant or the nascent Classical style. Though no original, he appears to have been a perfectly competent composer. But one does discern momentary lapses of judgement: a hackneyed sequence here, an awkward transition there, an opening fugato theme that overstays its welcome. Put him next to Friedemann Bach, who also taught him in Dresden, and the latter surely trumps him for expressivity (and avoids the solecisms just mentioned) even when nowhere near his most distinctive.

Ensemble Diderot are sympathetic advocates: I enjoy them most in the Friedemann sonata, which gives them more to play with, especially texturally (try the finale). The continuo is secure throughout, with Gulrim Choï’s cello grounding things solidly and expressively when called for. They inhabit the style very well, and the two violins are well matched, though sometimes sounding brittle at the top of their range. The concluding B flat major Sonata shows them and the composer they champion at their best, with a harmonic nudge or two away from the conventional in the final Chaconne.