This is a 1970s children’s book featuring a kind of hippie spy/hero who (may have) flown around on a magic cloud and had a base (?) in the Himalayas. He had an enemy called Jasper, who stole (all of the) music.

I heard this as an audio book on a cassette (where I recall a song with the words ‘Jasper, Jasper, where has all the music gone?’)