His first role was in Winterset, shortly after the end of the Second World War. His final role came a year before his death, when he appeared in Mamas Geburtstag. Both of these were television productions. He also appeared in many films, including Willy Wonka & the Chocolate Factory (1971), in which he played the minor role of a "tinker" who spoke to Charlie Bucket (Peter Ostrum) at the gates of Willy Wonka's chocolate factory during the first few minutes of the film.
Capell died in Munich, West Germany on March 3, 1986, aged 73. No cause of death was announced.