Dr Charles Burney, visiting CPE Bach in Hamburg, declared him ‘the best player [that ever existed], in point of expression’. 'He grew so animated and possessed,’ wrote Burney, ‘that his eyes were fixed, his under lip fell and drops of effervescence distilled from his countenance.’ Burney heard him playing a quiet Silbermann clavichord in his elegant music room. But he’d surely have been no less enthusiastic about the eloquent playing of Mahan Esfahani in his more ‘public’ performance of these relatively neglected Sonatas. Esfahani uses a Czech copy of a harpsichord from Bach’s time, with warm 4’ strings (an octave above written pitch). His excellent liner notes explain that these strings are plucked nearer the middle than is usual, giving a 'flute-like' and 'singing quality'. The effect is strikingly impressive.

The instrument is tuned with 'an amalgam of various temperaments’ (tuning systems). Despite an unequal temperament, which can make some of the less-often used keys sound out of tune, the instrument copes equally well throughout the wide range of keys that Bach calls for, including such extremes as B major (No. 6, second movement) and E flat minor (No. 5, Adagio). I suspect there may have been a little judicious tinkering with tuning between Sonatas to allow this; keys are distinctive and characterful, yet remain beautifully sonorous.

The Sonatas are remarkably varied. No. 1 opens with dramatic ‘Sturm und Drang’ (storm and drive) as Esfahani takes subtle liberties with the pulse to emphasise moments of silence. His exceptional sustained touch creates a warm legato in the second movement, while the third is alive with sparkling staccato.

He’s at his most expressive in the slow movements — the Adagio of the Third Sonata, the charming trio of No. 4, worked out as precisely as the three-part Sinfonias of CPE Bach’s father. The Fifth Sonata has barely established its home key before winding sinuously into noticeably remote areas. But the final Sonata, in B minor, is the most overtly expressive of all: the first movement becomes a rhythmically perplexing fantasia as powerful off-beat chords destroy the opening pulse; the second movement mixes languid sighs with questioning pauses; while the finale is a refreshingly simple two-part invention.

Mahan Esfahani has built his career to date on live performance in concerts, as artist in residence at New College, Oxford, as the first harpsichordist ever to give a solo recital at the BBC Proms, and as a conductor, director and arranger -his orchestration ofJS Bach’s Art of Fugue for the Academy of Ancient Music had its premiere at the 2013 Proms. This, his first solo disc, provides a particularly welcome introduction onto the world stage for an artist matching, in expression’ CPE Bach himself.