Piano concertos by Wolfgang Amadeus Mozart it was probably J.C. Bach, whom Mozart admired, who introduced the structural innovation of allowing the keyboard to introduce new thematic material in its first entry. Concertos Nos 1–4 (K. 37, 39, 40 and 41) are orchestral and keyboard arrangements of sonata movements by other composers. The next three concertos (K. 107/1, 2 and 3), which are not numbered, are arrangements of piano sonatas by J.C. Bach (Op 5. Nos. 2, 3, and 4, all composed by 1766). Based on handwriting analysis of the autographs they are believed to date from 1771–72. Concerto No. 5, K. 175 from 1773 was
Organ concertos, Op. 4 (Handel) of his oratorios Esther and Athalia. During this period Handel prepared the 16 movements of the four organ concertos HWV 290-293, of which 10 are reworkings of previous compositions with the remaining 6 largely newly composed. HWV 292, completed in March 1735, contains the most new material, although even there the ritornello of the first movement is a borrowing from Act 1 of Alcina. It featured in the April performances of Athalia at Covent Garden. The other concertos were first heard in March, HWV 290 and 291 in Esther and HWV 293 in Deborah. Handel completed Alexander's Feast in January