Terzetto is a 1925 work for Flute, Oboe and Viola by Gustav Holst. It is scored in two movements: Allegretto - Andante and Un Poco Vivace. Described by the composer's daughter and biographer as his only "successful" chamber work, it is renowned for having all three instruments playing in different keys at the same time.
Gustav Holst (1874-1934) was an English composer and teacher. Having studied under Stanford and Parry, he became a close friend of Vaughan Williams – they would often critique each other’s work – and influenced composers such as Tippet and Britten. He is best remembered for his Planets suite.