Having drawn on and developed charateristics of Façade in the robust, jazz-inspired rhythms of the overture Portsmouth Point (1925) and in the lassitude of Siesta for small orchestra (1926), Walton finally felt prepared to tackle a full-scale instrumental work in the Sinfonia Concertante for orchestra with obbligato piano (1927), themes from its three movements, which are portraits of the Sitwells, exhibiting a suitable family likeness. Stylistic maturity came with the richly poetic Viola Concerto (1929) and the ultravirtuosic Violin Concerto (1939), between which Walton wrote two other masterpieces, the oratorio Belshazzar's Feast (Osbert Sitwell, after Bible, 1931), pagan in tone, violent and savage, and the First Symphony (1935). In both works Walton revitalized traditional genres, and in the latter he provided a twentieth-century counterpart to the Beethovenian symphonic model of initial conflict finally resolved in triumph.
The Second World War marks a watershed in Walton's output, because, although he gained in fluency through being involved in film music - he completed six film scores between Major Barbara (1941) and Henry V (1944) - there is, to a certain degree, a loss of conviction, and the quality of the masterpieces of the 1930s is matched only is such works as the String Quartet in A minor (1947), the Cello Concerto (1956) and the Variations on a Theme of Hindemith (1963). Other works, such as the Improvisations on an Impromptu of Benjamin Britten for orchestra (1969), where manner takes precedence over matter, are less inspired.