It is surprising that the mighty Diabelli Variations has had so few recordings on a period piano since Arkiv’s pioneering set by Jörg Demus in 1978 (now available on Eloquence; an interesting set that included 32 of the 50 other variations of Diabelli’s anthology). Andreas Staier raised the bar with his 2012 recording on Harmonia Mundi: a revelatory reading, taking every opportunity to exploit the varied colours of his instrument, but his liberal use of the moderator and Janissary pedals might be too much for some listeners.

Collectors of Ronald Brautigam’s superb complete survey of Beethoven’s keyboard output have been eagerly awaiting his account for its concluding volume and I doubt they will be disappointed. He uses yet another superb Paul McNulty instrument; this time a copy of an 1822 Conrad Graf that approximates that which Graf presented to Beethoven in 1826 – with four strings per note. Its lovely limpid treble points forward to later pianos but retains the fortepiano’s nut-brown colour in mid and bass registers – and it sounds glorious thanks to the state of the art recording.

Brautigam allows the beauty of the instrument to shine, using its particular tonal characteristics to illuminate chord voicings and rhythmic details without interrupting the musical flow. Tempi are fleet but perfectly judged and the clarity of his articulation is such that one could write down the score – if you could keep up!

He coaxes otherworldly sonorities that enhance the strangeness of Beethoven’s transmutations – the Var. XXIV Fughetta’s ethereal musing is something special to treasure. He shies away from the effects pedals, so is more inclined to let the music convey Beethoven’s amused toying with Diabelli’s innocuous little tune – a knowing wink and nudge rather than Staier’s uproarious guffaw.

Carefully controlling the ebb and flow of the unfolding drama while keeping an eye on the distant horizon, Brautigam keeps a clear head throughout. So many fall at the home straight; the slightest mistiming and the structure can fail – Staier is just a little too ruminative in Var. XXXI and tension dissipates slightly in the Fugue – but Brautigam perfectly judges the arc so that the Minuet is a magical release and the finale winds down to a pensive leave-taking.

The disc concludes with a selection from Beethoven’s money-spinning venture to arrange folksongs for the parlour – mere fluff, but Brautigam’s affectionate care makes for genial entertainment. This is a satisfying conclusion to a project of great integrity and a library essential.