Although the manuscript for the B-flat major concerto is written almost entirely in Leopold Mozart's handwriting, scholars still attribute the arrangement to his son, who, quite possibly, improvised the solo piano part of the concerto for his father to write out. The original material is credited to Hermann Friedrich Raupach's first piano sonata (for the outer two movements of K. 39) and Johann Schobert's Op. 17 no. 2 (for the second movement of the concerto). This practice of piecing together works from different works of different composers for each movement is known as "pastiche", and was found in the first four piano concertos of Mozart. Although study of the concertos will not accurately reveal Mozart's compositional ability at age 11, it will reveal a surprising understanding of orchestral color and interplay, especially in the concerto medium.
The first movement is very stately and regal, employing much use of the French horn. This prominent role of the horn is found in the friendly Andante movement, which, after its more dramatic opening unison, warms up to be very pleasant and charming. The finale continues with the character of the first two movements-confident and agreeable, but not too flashy. The third movement also continues in the use of the horn, thus demonstrating Mozart's ability, if not in composing, then constructing a piece with unity of character and instrumentation throughout.
No. 2 (K. 39) in B flat major
The concerto is scored for strings, piano (or harpsichord), and pairs of oboes and horns, as above. The movements are:
- Allegro spiritoso 44
- Andante - in F Major 44
- Molto allegro 24
The first and third movements are again from Raupach (Op. 1, No. 1), whilst the slow movement is based on the opening movement of Johann Schobert's Op. 17, No. 2, a composer admired by Mozart.
