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Due to an industrial dispute over extra payments for using newly-introduced colour equipment in which broadcasting unions refused to allow their members to use colour cameras, the first six episodes of the first series were shot in black-and-white, and when colour production resumed, the first episode was remade in colour. Two endings were made, which could be shown depending on whether or not the black and white episodes were broadcast by the channel. The original black-and-white first episode is believed to have been wiped.