When he was two, the family returned to live in Viskafors, Sweden, and William began studying violin and singing at a music conservatory in Borås.

Four years later, he won the title of "All American Boy" at the Hollywood Bowl, and began taking occasional small uncredited acting roles in movies including Abbott and Costello's The Wistful Widow of Wagon Gap (1947).

He moved to Sweden in 1954, married, and made his first recordings in Stockholm with the orchestra of Lille Bror Söderlundh.

He worked extensively in Mexico with the Trío Calaveras, becoming known there as "El Charro Guero" (the blond cowboy).

[2][3] In the late 1960s he opened a Mexican restaurant in Stockholm, before returning to live in the US, where he began collecting and performing cowboy songs.