Among the manuscripts that Harriet Cohen bequeathed to the British Library in 1967 was the score of a four-movement keyboard sonata in Bax’s handwriting (Add. MS 54767). The separate title page has the heading, Sonata in B♭ major (Salzburg). To the left of the title on the first page Bax has written, “Date: (conjectured) circa 1788”, and to the right, “Author unknown”. Suspicions that this is no transcription of an anonymous 18th-century work are aroused by the appearance in the second movement of a passage that occurs in the slow movement of Bax’s Violin Concerto (1937–8), and confirmation was provided by Alan Richardson, an acquaintance of the composer, who met him on a bus some time in the early summer of 1937. Bax told him that he was working on an 18th-century pastiche, perhaps as a musical purgative after the drudgery of orchestrating his recently completed march, London Pageant, at the end of which he had written, “Fine (thank Heaven!)”. A sketch for the opening of the Violin Concerto’s slow movement appears on the last folio of the sonata, which ties in with 1937 as the year of composition. Bax never submitted the sonata for publication, and no public performance took place until 21 April 1983, when Jonathan Higgins played the slow movement during a lecture-recital at the British Music Information Centre.