During the composition of The Planets, Gustav Holst wrote the Japanese Suite at the request of Michio Ito, a Japanese dancer.
Michio Ito wanted to dance to a work derived from traditional Japanese. However, Holst didn't know any traditional Japanese music, so Michio Ito had to whistle several to him.
(Note: As of 2006, all musical works by Host entered Public Domain in all countries. Music recordings however are still subject to copyright laws.)