Doctor Who (series 4) Astrid Peth, who died during the events of the episode. The companions in the regular series had all been in the lead companion role previously: the primary role of Donna Noble, who was introduced in "The Runaway Bride", was played by Catherine Tate for all thirteen episodes. Her return was announced by the BBC on 3 July 2007. Freema Agyeman, who portrayed the Doctor's companion Martha Jones in series three, returned for "The Sontaran Stratagem", "The Poison Sky", "The Doctor's Daughter", "The Stolen Earth" and "Journey's End". Billie Piper, who played Rose Tyler from the first episode of the new
Doctor Who (series 1) the BBC. Davies voluntarily wrote a pitch for the series, the first time he had done so; he previously chose to jump straight to writing pilot episodes because he felt that a pitch would "feel like [he's] killing the work". The fifteen-page pitch outlined a Doctor who was "your best friend; someone you want to be with all the time"; the eighteen-year-old Rose Tyler as a "perfect match" for the new Doctor; avoidance of the forty-year back story "except for the good bits"; the retention of the TARDIS, sonic screwdriver, and Daleks; removal of the Time Lords; and also a