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
The Doctor (Doctor Who) Ninth Doctor already regenerated and fully stabilised, with no explanation given. In his first appearance in "Rose" (2005), the Doctor looked in a mirror and commented on the size of his ears, suggesting that the regeneration may have happened shortly prior to the episode, or that he has not examined his reflection recently. Some draw the conclusion that the Ninth Doctor's appearances in old photographs, without being accompanied by Rose, may suggest that he had been regenerated for some time, but these appearances could have occurred afterwards. Russell T Davies, writer/producer of the new series, stated in "Doctor Who Magazine"