The first ‘Allegro’ of K424 is preceded by a magnificent slow introduction, based on a motif that Mozart was to re-use four years later in the slow movement of the G minor String Quintet (K516). The main part of the movement is one of a long series of triple-time allegros in B flat (the Divertimento K287, the Symphony K319, the unfinished Clarinet Quintet movement K516c, the Piano Sonata K570 and the String Quartet K589 are some of the others) which all exhibit a similar lively yet lyrical mood and show remarkably similar formal designs. The wide variety of melodic ideas in K424 is especially appealing, and, as contrast, there is some particularly brilliant concerto-style passagework for the violin, and a development whose climax is a spirited canonic episode, where viola and violin each take the lead in turn. The following ‘Andante cantabile’ is a single extended violin melody. Two features are especially remarkable: the rich harmony that the viola, usually playing two notes at a time, is able to suggest, and the lack of emphasis on the cadence points. This creates a free, romantic style of lyricism. The outlines of the last movement, an ‘Andante’ with six variations, are by contrast absolutely clear, with a different character for each variation and a coda that transforms the theme into a lively German dance. The viola shares in the presentation of the initial theme and has a leading role in several of the variations.
from notes by Duncan Druce © 2001