The Colour Strike was an industrial action by technicians at ITV companies which ran from 13 November 1970 to 8 February 1971.
At that time, ITV had recently switched to colour transmissions, requiring the individual companies to invest heavily in new equipment.
Early colour television studio cameras consisted of four tubes to relay the picture: three were receptive to colour (red, green and blue – the chrominance signal) with the fourth providing a high-resolution monochrome image (the luminance signal).
During this time, ATV showed a modified version of its regular caption slide An ATV Colour Production at the end of its shows, which had the word 'colour' blanked out, with Granada's regular caption slide also omitting the words 'Colour Production' to reflect this fact too.
[citation needed] There was also a short dispute two years later in early 1973; this affected both BBC channels as well as ITV.