He had some success in the US by 1965, but it was his collaboration with producer Mickie Most who had been doing work with Lulu, The Animals, and Herman's Hermits. Donovan's first collaboration with his new producer brought him the song, "Sunshine Superman". Which became a number one song for him in the states.
"Superman" was inspired by Linda Lawrence, who became his muse throughout his late 60's output, and later became his wife. It was full of the trippy, psychedelic folk sound that became a trademark of his music. It began a string of top 40 hits that would lead him to the end of the decade.