This release of Rosalyn Tureck’s live traversal of Book 1 of Bach’s ‘48’ for BBC Radio 3 – spread across four sessions (six Preludes and Fugues in each) between September 1975 and April 1976 – complements her landmark 1953 studio recording, reissued on DG three years ago to great acclaim. It makes for fascinating comparison. As is characteristic of Tureck’s Bach, she combines technique with expression in way that makes one barely aware of the physicality of her playing. Her range of articulation is something to marvel at and her judicious use of both pedals enables a range of timbre and colour that brings the music to life. Try Prelude No 6, where the way she varies her colour and dynamic suggests changing manuals on a harpsichord, or stops on an organ. Indeed, the truth of Tureck’s playing transcends her choice of instrument.

Tureck creates a marvellous atmosphere of stillness in the E minor Prelude (No 10, the one arranged and transposed by Alexander Siloti), and her dazzling articulation of Prelude No 11 reveals both a pristine clarity of line and an invigorating range of semi-staccato delivery: it’s hard to imagine anything further from the typewriter school of mechanical Bach playing. Her approach is not radically different from 1953, but there is an added vividness here and her emphasis on the music’s character is bolder and more assertive, conveying a greater sense of spontaneity.

Some of the tempi in the fugues are rather measured, and whereas Edwin Fischer’s joyous account is glossed with a more Romanticised hue, Tureck’s playing sometimes takes on a quasi-religious dimension. There is a fine line between the austere beauty in Fugue No 12 and her uncompromising, slightly aggressive stance in Fugue No 20, while her sombre pathos in the miraculous final Fugue (No 24) is wonderfully poised.

Occasionally I find myself feeling more admiration than affection. Certainly the way Tureck announces the fugal entries will bother some people, although I find her approach is less calculating here than before, the interpretation largely free of the self-concious academicism that occasionally hovers over the earlier recording. The sound, although varied between the sessions, is inevitably better too. A must for Tureck fans, this important release reconfirms her status as one of the defining Bach interpreters of the last century.