Piano Concerto in C major, K.503

No Mozart concerto has a more imposing beginning than that of K.503. The audience which heard the composer give the first performance of the work - probably just a day after he had completed it in Vienna in December 1786 - must have realised from the start that they were about to hear something of unusually ambitious proportions. In fact, the opening Allegro maestoso is the most expansive of all Mozart’s concerto movements. Its structure does not depend, however, on that grand introductory gesture, which is heard only twice more and even then only as a formality. What interests Mozart more, obsesses him even, is a nagging little motif heard on first violins as oboes and bassoons turn from the opening proclamation of C major to a matter of more private concern.

That nagging motif, identified by its three repeated quavers, occurs literally dozens of times in the following orchestral passage. It also turns up as the first three notes of what amount to the main theme of the movement - very much in the style of the recently first-performed Marriage of Figaro - quietly introduced by violins in C minor. There are several more allusions to it before the magically contrived first entry of the piano. So it goes on, nagging at the rest of the exposition, in spite of the profusion of alternative melodic interest offered by both the soloist and the orchestra, and haunting a development section devoted otherwise to passing the main theme in a variety of harmonies between piano and woodwind soloists. The opening gesture returns to signal the beginning of the recapitulation where, inevitably, the three-note motif retains a high profile but where, masterfully, the recall of the main theme is held back until oboes and horns pounce on it in a joyful C major and completely transform the atmosphere.

Scarcely a cloud passes over the slow movement - a semi-operatic moonlit nocturne as beautifully scored for the orchestra as it is for the piano. The first theme is introduced mainly by woodwind, with atmospheric horns in the background, and offset by a delightful little passage with rustling second violins and discreetly excited comments from first violins above them. The same material is taken up by the piano, with some additional colouring from the winds, before a middle section where Mozart left himself scope for improvisation - or so it seems from the sparse-looking piano part, although every soloist is free to interpret the implications of the score in his or her own way here.

The mood of the closing rondo is set by its main theme, a rhythmically mischievous dance tune borrowed from the Idomeneo ballet music and presented here by violins in the opening bars. The material introduced by the piano is no less cheerful but after the first return of the rondo theme the soloist becomes rather more serious, particularly where an expressively syncopated piano melody invites sympathetic comments from oboe and flute and an intimately romantic counterpoint from the cellos. A second return of the rondo theme restores the carefree mood, however, and there is room for only brief allusions to the syncopated melody from the central episode before the movement reaches its emphatically happy ending.