Trade test colour films were broadcast by the television network BBC2 in the early days of colour television in Britain during intervals when no regular programming had been scheduled. The goal of these transmissions was to provide colour broadcasting in these intervals for use by television shops and engineers (the 'trade') to adjust their television sets. The earliest such transmission was made in 1956 (on the then sole BBC channel) but regular all day long films ran from autumn 1967; the last one was in August 1973. In all, 158 different films were broadcast; on average, each film was shown 90 times.
The frequent broadcasting of the films made them well known to viewers of the time. The one most frequently shown was The Captive River (1960), which was shown 525 times. The short film Giuseppina (1959), which had won an Academy Award, was shown 158 times and became the last trade test colour transmission on August 24, 1973. Other frequently broadcast films included The Home Made Car (1963), The North Sea Quest (BP, 1967), Overhaul (1957), Crown of Glass (1967), Roads to Roam (1967), The Small Propeller (BP, 1967), The Cattle Carters (BP, 1962) - with a theme song sung by Frank Ifield, Prospect for Plastics (1962), Evoluon (1968) and Cantagallo.
A number of these films were produced by the oil company BP, including We've Come a Long Way (1951), The Shadow of Progress, Newspaper Run, and Skyhook. Other films included Paint (produced by Shell), Study in Steel (produced by British Steel Corporation), Algerian Pipeline (Constructors John Brown Ltd), The Captive River (Shell), Ride the White Horses (Ford Film Unit), Something Nice To Eat (the Gas Council), It's The Tube That Makes The Colour (Mullard), On the Safe Side (1967, UKAEA), Oil Underground (1960, Shell) and Transport Ability (UKAEA). Another film, Birth of a Rainbow (1967), about trout farms, was made by the New Zealand National Film Unit, while Network (1962) was made by the AEI, and No Claim Bonus (1963) was made by the COI. The Gold Miners was made by Films of Africa, and A Journey into the Weald of Kent (1959) and Beauty in Trust were made by the National Benzole Company with narrations by Sir John Betjeman.