teenager. The British media regularly released conflicting reports about how long Piper would be staying with the programme. In March 2006, it was suggested that she would continue on Doctor Who into its third series in 2007. However, the BBC announced on 15 June 2006 that Piper was to depart in the final episode of the second series, "Doomsday". Her decision to leave had been taken a year previously. Following "Doomsday", Piper as Rose was greenlit to be the star of the spin-off series Rose Tyler: Earth Defence, set in her parallel universe and to air as a bank holiday special, but Davies deemed the concept "a spin-off too far" after Torchwood and The Sarah Jane Adventures. Piper's eventual return during series four was planned during filming of the second series; in January 2006, she made a pact promising to return to film several more episodes. Davies and Piper cited her commitment to other projects—specifically, her roles as Belle de Jour in Secret Diary of a Call Girl, the lead character in the BBC adaptations of Philip Pullman's Sally Lockhart quartet, and Fanny Price in the ITV adaptation of Mansfield Park—as explanations behind her departure appearing permanent. Davies' successor as executive producer, Steven Moffat praised the creation and casting of the character in advance of the series' 50th anniversary in 2013. He stated that the character of Rose helped secure the return of the show by allowing "an audience who would not naturally have watched Doctor Who" to become invested in the show. Moffat suggested that during the first two years of the revival Doctor Who "was Billie Piper’s show" and that this has given her an "iconic status" above other Doctor Who companions. Characterisation Rose is used by Davies as an introduction to the show's mythos and fantasy elements. He later underlined similarities between Rose and Gwen Cooper —the lead for Torchwood — describing both as "the ordinary person who stumbles into something extraordinary and finds herself their equal." Like her successor Martha, Rose is from London; Brett Mills from the University of East Anglia makes the assumption that this is because characters from the capital of the country are "relatable to all British people" because they are seen as "neutral". Rose is introduced alongside a supporting cast in the form of her boyfriend Mickey and mother Jackie which James Chapman cites as "evidence of Davies' attempt to create