Like APR’s earlier release of Hambourg’s complete Liszt Hungarian Rhapsodies (1/06 – a gramophone first), this selection of 49 different works (51 tracks) veers from electrifying to execrable, from inspired to banal. Try as one might to justify this pianist’s shortcomings by placing them in a historical context, due either to technical failings or musical conception or sometimes both together there are some truly awful performances on these two CDs which none of his peers would have countenanced releasing (Hofmann, Cortot, Petri and Schnabel were Hambourg’s almost exact contemporaries).

Look no further than the transcription of Bach’s Prelude and Fugue in D, BWV532. Eugen d’Albert’s intention was to transfer the organ’s grandeur and sonority to the piano, not to provide a mindless, scurrying perpetuum mobile. (Piers Lane shows, thrillingly, how it should be done – Hyperion, 6/10.) Claire de lune, with an average performance time of around five minutes (Gieseking, Bavouzet, dozens more) is here brushed aside in under three; the unsteady pulse of many numbers with their constant speeding up and braking becomes irksome. I could go on.

And yet, and yet. There is frequent evidence of a big personality, of an exciting expressive impetuosity and of fabulously fluent fingers (even if clarity is sometimes compromised by the acoustic process): The Harmonious Blacksmith, for example, and Moszkowski’s Étude in G flat (Hambourg’s 1929 recording preferred to that of 1909), even if Seta Tanyel’s less flamboyant 1996 account is more musical (Hyperion, 12/96, A/02). Very often you will hear the beautiful singing tone for which Hambourg (and his fellow Leschetizky pupils) was famed: try Schumann’s ‘Schlummerlied’, the Gluck-Sgambati Mélodie and ‘Ondine’ from Gaspard de la nuit (the first recording by all of 16 years, albeit abridged), all of them quite gorgeous.

Many of the rarer titles, too, have an undeniable charm (Rimsky-Korsakov’s ‘Dance of the Tumblers’ and the Intermezzo from Wolf-Ferrari’s The Jewels of the Madonna). Indeed, for pianophiles perhaps the greatest draw of this release is the repertoire. There are works by Byrd, Bull, Blow, Arne and Couperin (who else was recording them in 1915?); Leonard Borwick’s transcription of Prélude à L’après-midi d’un faune of which Hambourg gave the world premiere; first recordings of Rachmaninov and Scriabin; and works by Poldini, d’Erlanger and Anton Rubinstein – the pianist to whom Hambourg was most often compared – whose Étude in F, Op 23 No 1, was the last recording Hambourg made. That was in 1935, a full quarter of a century before his death.

In short, pianophiles should not hesitate over this invaluable cabinet of curiosities. Others should.