The story also introduced the Doctor's binary vascular system, which would become an oft-repeated feature of Time Lord physiology thereafter. Moreover, it premiered the Nestene and the Autons, who would reappear in future stories. Russell T Davies would later use this story as a template as he wrote the first episode of the 2005 series. It also had some commonality with Steven Moffat's first story as producer, in that both this story and The Eleventh Hour would introduce a new Doctor and new companion after the departure of those from the previous story, effectively making a "clean break" from the previous era of the show.