Did Bach really leave ‘Contrapunctus 14’ of The Art of Fugue unfinished? Two scholars think otherwise. Christoph Wolff argues that the composer ‘planned to stop where he did’. And Hans-Klaus Jungheinrich, believes that ‘the fugue is imposing enough to be a plausible climax’. The Keller Quartet, playing modern instruments, are indeed imposing, but the marking alla breve indicates a need for more vitality – which Fretwork offer.

The wide variation here exemplifies the absence of tempo directions for the 20 pieces that comprise this work. Performers are expected to relate speed to time signatures without other guidance; and Fretwork’s judgements are difficult to fault. Turn to the ‘Canon alla Duodecima’, or alternatively ‘Contrapunctus 9’, where the required swift pulse does not preclude expressive articulation; and then to ‘Contrapunctus 10’, where four-in-a-bar is reflected in a slower pace that also allows more space for a keener, but not overt, subjective response. Indeed, throughout their idiomatically phrased, impressively cohesive and clean-textured exploration of the work, these thoughtful musicians don’t italicise anything.

In sum, the Keller are extrovert in their emotional involvement, whereas Fretwork opt for a quieter, controlled intensity that perhaps needs extended listening to be fully appreciated. The recording certainly won’t stand in your way. It is expertly balanced, the acoustic of The Maltings, Snape harnessed to give both ambience and intimacy. Producer/engineer Nicholas Parker has done Fretwork proud. Bach, too. Though The Art of Fugue is usually considered a composition for keyboard, the timbre of strings, especially viols played and reproduced this way, does give the music another dimension.