 An expensive film to produce, Granpa is hand-illustrated with coloured pencil, imitating Burningham's style in the book. It was directed by Dianne Jackson, who had previously adapted The Snowman by Raymond Briggs (1978), a wordless picture book, as an exceptionally successful family-oriented animated film (1982). Howard Blake, who wrote the music for the The Snowman, wrote the music and the script for Granpa, which is referred to as an "animated children's opera". The voices of Granpa and Emily are by Peter Ustinov and Emily Osborne.
