Unlike Beethoven, whose deafness drove him from the concert platform relatively early in his career, Johann Nepomuk Hummel remained one of Europe's most celebrated virtuosi until the early 1830s. His longevity as a performer owed as much to his vigour and resourcefulness as a composer as it did to his formidable technique as a pianist. Like Beethoven and Mozart before him, Hummel was an exceptional improviser and improvisatory techniques are to be found in many of his published works for solo piano. They also find their way into a number of works for piano and orchestra. The Variations in F, Op.97 of 1820, for example, consists of a theme and set of variations whose structural regularity is destabilized by the orchestral links between variations, the inclusion of a lengthy free variation at a slower tempo and an interpolated cadenza prior to the final variation. This fluidity of structure owes much to Hummel's improvisatory practices and imbues the work with a sense of spontaneity that adds considerably to its charm.