The boldly assertive opening Allegro of No 41 is the only movement in the three Marie Esterházy sonatas in full sonata form. Its second group of themes begins with a radical reinterpretation of the first before moving to F minor for a new, restlessly modulating theme over an Alberti-style bass. As in the finale of No 40, the development immediately dips a major third to a relatively distant key (here D flat after F)—a favourite dramatic ploy of Haydn’s in the 1780s and 1790s. Almost before we have got our bearings, the music swerves abruptly to an equally surprising E flat major for a restatement of the main theme. Haydn follows this Allegro with a movement both mercurial and tautly worked, often freely contrapuntal in texture. Its form (ABA, with the ‘A’ section playfully varied on its reprise) is akin to the finale of No 40, though here the central section, in B flat minor, begins as a free paraphrase of the opening.
It is a far cry from these delectable lightweight works composed for amateur domestic performance to the large-scale sonatas written during Haydn’s second London visit of 1794–5 for the professional pianist Therese Jansen (c1770–1843). Born in Aachen, Jansen became a star pupil of Clementi’s after her move to England. Haydn warmly admired her playing, composing for her not only the sonatas Nos 50 and 52 (possibly, too, the slighter D major, No 51) but also three of his greatest piano trios, Nos 27–29. In May 1795 he was a witness at her wedding, in St James’s Piccadilly, to the picture dealer Gaetano Bartolozzi, son of the famous engraver Francesco Bartolozzi.
from notes by Richard Wigmore © 2007