Boismortier’s Op. 21 was intended for a flute, a violin or second flute, and basso continuo (with a musette or recorder proposed as alternatives to the flute in Concerto No. 3), but the deliberately generic writing and limited range of the treble parts means that the works are playable on a variety of instruments. Boismortier has also provided an ‘ad lib’ ripieno part for a third (unspecified) treble instrument which mainly doubles the flute in the ritornellos; even though this part is optional...