Serious record collectors should regularly light a candle for Robert von Bahr whose label BIS has brought so many fine artists to our attention; his willingness to green-light projects of dubious financial return is much appreciated by those of a completist turn.

Ronald Brautigam’s surveys of Haydn and Mozart keyboard works were distinguished not only by the exceptional performances of the major masterpieces as by his diligent attention to every extant scrap from the composer’s desk. This latest release in his Beethoven cycle includes some of Ludwig’s least inspired scribblings but does have some gems to treasure. The lesser works can be a bore on a modern piano so the lovely characterful sound of the period instrument, an impeccable copy of an 1819 Conrad Graf by Paul McNulty, does wonders for their charm factor. This particular instrument featured heavily in earlier volumes and is a magnificent device with a lovely liquid top register and engagingly nut-brown bottom-end.

Brautigam wrings the maximum expression and colour out of the instrument without ever pushing through the tone, while the light action abetted by his superb technique make for some thrilling flourishes. For the slyly charming variations on God Save the King, Rule Brittania and...