Piano rarities rule the roost in this long-anticipated release. Let’s start with its rarest of rarest, a portion of the Beethoven Op 10 No 3 Sonata’s slow movement in a strikingly free and conversational recording from around 1921 by Brahms’s close friend Josef Labor (1842-1924). Other scarcely known pianists include Iso Elinson in an effortlessly tossed-off 1932 Chopin double-thirds Étude and Stanley Hummel in 1960 gorgeously singing out the Glinka/Balakirev The Lark.

We hear Ivan Davis sailing through Liszt’s ‘La campanella’ on a television show promoting the infamous Siena Pianoforte, later revealed to be just a modern upright. Veteran Liszt pupil Moritz Rosenthal’s uneven last recording sessions yielded a strong, recently discovered take of Chopin’s E minor Waltz. A rejected 1927 test pressing with Alfred Cortot in Stravinsky’s ‘Russian Dance’ from Petrushka abounds with wrong notes, yet it conveys great character – and notice the beautifully shaded left-hand scales.

I don’t share Benko’s enthusiasm for Leff Pouishnoff’s rather workaday live 1946 Rachmaninov Second Concerto; nor do I hear anything in Ervin Nyiregyházi’s 1978 Schoenberg Op 11 No 2 beyond ponderous pounding, despite his uncanny dynamic range. Yes, the composer was dumbstruck by the pianist’s interpretation in 1935, but that was then. However, a previously unpublished 1931 Mendelssohn Variations sérieuses testifies to the young Abram Chasins’s breathtaking mastery.

Nineteen minutes survive from a smouldering live 1932 Horowitz/Fritz Reiner/Philadelphia Orchestra Tchaikovsky First Concerto, captured by Bell Labs in amazingly vivid sound for the era. Two brief rehearsal snippets with Horowitz letting off steam, however, are chicken soup next to a recording session mini-drama where Guiomar Novaes simultaneously argues with her producer, threatens to leave her record company and practises Chopin’s Berceuse at half tempo in different keys. She’s redeemed by a winged and songful live 1950 Mozart K271 Concerto. Extensive booklet notes recount the fascinating stories behind each recording. Let’s hope that Marston’s Landmarks project will prevail beyond Vol 1.