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) without the shagging". He later stated that Rose was the Doctor's girlfriend, though it was never explicitly stated on screen. The Doctor's relationship with Rose intensifies after he regenerates into the Tenth Doctor. In "New Earth" (2006), Rose's body is temporarily inhabited by Cassandra, who kisses the Doctor romantically. This is one of the few scenes in the entire programme where the Doctor is kissed romantically by his companion. In "School Reunion" (2006), the arrival of the Doctor's previous companion Sarah Jane Smith and his reaction to seeing her again prompts jealousy and worry from Rose, and Sarah all but