Two opinions: from Richard Egarr that the Goldberg Variations ‘are ultimately symbiotic with the sound world of the harpsichord’; from Robert Costin that, ‘given Bach’s mastery of the instrument, arguably he would have been much less surprised to hear it on an organ than on a modern piano’. Would he? In his last years Bach helped Gottfried Silbermann improve and sell his fortepianos. Played one too for Frederick the Great at Sanssouci. Should a pianoforte have occasioned astonishment?

Moot point; yet since the first recording of the work in 1933, harpsichord and piano have spread the word. On current showing the organ is unlikely to do so. Its sustained sonority certainly beguiles in the Aria. Costin portrays a stately Sarabande but one characterised by a prominent top line. Other lines are subservient, low in volume and vague in definition, an inequality that acquires greater import in the first two variations – two- and three-part inventions – and beyond. Many, like Vars 9 13, are subject to the monotony of blurred parts and unclarified textures, the treble again dominant in the four-part fugue of Var 10. Fingers aren’t always ideally precise; the triplets in Var 20 almost fall over themselves. Conversely, a lugubrious gait does little for Var 15 (Andante in G minor) or Var 25 (‘Black Pearl’). There are fleeting moments when the organ may appear suitable but otherwise lofty intentions are doomed from the beginning.