Doctor's tenure. Dicks had, however, been the uncredited co-writer of the earlier serial The Seeds of Death (1969), having extensively re-written Brian Hayles' original scripts. Dicks formed a highly productive working relationship with incoming Doctor Who producer Barry Letts, serving as script editor on all of Letts's five seasons as series producer from 1970 to 1974. During his tenure as script editor on Doctor Who, Dicks oversaw a number of additions to the program's mythology that still exist in the modern era including the following: The development of the Time Lords and their society. The name Gallifrey (augmented from Doctor Who writer Robert Holmes' "Galfrey"). The creation of companions Liz Shaw, Jo Grant, and Sarah Jane Smith. The term "regeneration". (Planet of the Spiders) An established race of villainous monsters turn to the side of good. (the Ice Warriors in The Curse of Peladon by Brian Hayles) Sontarans (from writer Robert Holmes). The Dematerialisation Circuit is vital for the operation of the TARDIS. The concept that the TARDIS is indestructible. The TARDIS can be remote controlled. The TARDIS has a Telepathic Circuit (in The Time Monster) The TARDIS might be sentient (The Time Monster and Planet of the Spiders) The Blinovitch Limitation Effect used as a plot device to explain away paradoxes. (Day of the Daleks) Multi-Doctor stories. (The Three Doctors) During Dicks' tenure, the program also delved into social and political concepts. Sometimes these were straightforward and other times they were metaphors. Concepts and topics included the respect for all life (The Silurians), Great Britain joining the European Economic Community (in metaphor in The Curse of Peladon), apartheid (The Mutants), global pollution (The Green Death) and equality for women (with the inclusion of Sarah Jane Smith as companion). In 1972, Dicks embarked on a parallel career as an author with the publication of his first book, The Making of Doctor Who (a history of the production of the TV series), which was co-written by Hulke. After stepping down as script editor, Dicks continued his association with Doctor Who, writing four scripts for his successor, Robert Holmes: these were Robot (1975, Tom Baker's first outing as the Fourth Doctor), The Brain of Morbius (1976, for which Dicks was credited under the pseudonym Robin Bland after his displeasure at Holmes' re-writes prompted him to request that it be shown "under some bland pseudonym"), Horror of Fang Rock (1977) and State of