Who Composed K. 626b/16, and Why Would Mozart Write It Down?

In conjunction with Wolfgang Amadé Mozart's 265th birthday on 27 January 2021, the Salzburg International Mozarteum Foundation presented a premiere performance and an online edition of the recently rediscovered Allegro in D major for Piano, K. 626b/16. While the authenticity of the document and of Mozart's handwriting appears to be beyond doubt, Mozart's authorship has been designated "conjectural" in the RISM data released alongside the piece's edition. In this study I set out to examine the question of authenticity of this miniature, demonstrably a piano reduction of an orchestral composition, from a style-analytical perspective. Some aspects recall Mozart's London Sketchbook, dated almost a decade earlier than the editor's proposed dating for K. 626b/16, 1773; however, no compelling connection between the two can be established. The piece's midway position between a sonata-dance and a sonata-allegro movement, and its particular employment of voice-leading schemata and musical punctuation, deem Mozart's authorship unlikely. I discuss its possible origin as a ballet number in conjunction with the genres of the chaconne and the stage minuet. Borrowings from K. 626b/16 are identified in both the first movement of Mozart's Symphony K. 128 and the closing chorus of Lucio Silla, suggesting a date no later than the first months of 1772. Elements of the piano piece resurfacing in later well-known Mozart works substantiate its lasting influence on the composer.