27 October (production)


 * 1970 - Script editor Terrance Dicks wrote to writer Louis Marks about Marks' story idea for Day of the Daleks, "the addition of the 'going into the future' storyline gives it the added science fiction feeling that we need." He however explained that he had not yet been given to all-clear to commission another season, and thus could not yet commission his storyline. He finally gave the order on 22 January 1971.