A high speed Inter-City train is the star of this impressionist film in which picture and music are brought together to enhance the mood and rhythm of the subject and hail the arrival of 125mph regular passenger services. With specially composed music by David Gow and no commentary, Overture: One-Two-Five was the last complete production to be shot on 35mm film by British Transport Films. It was produced to mark the introduction of the new Inter-City 125 High Speed Train services between Paddington and Bristol. One of the last big budget productions, it was treated to a coat of Technicolor and a theatrical cinema release. It also marked the beginning of the slow decline of BTF which culminated in its closure. With the abandoning of support features and shorts at cinemas in the late 1970s and early 1980s, most of the unit’s films after 1978 were made primarily for internal use.