The Doctor (Doctor Who) Time Lords a fixed number of twelve regenerations, meaning that every Time Lord had a total of thirteen incarnations including the original. The plot of "The Time of the Doctor" involves the Doctor receiving a new cycle of regenerations from the Time Lords before his expected demise, triggering the regeneration into the Twelfth Doctor, played by Peter Capaldi. The origins of the programme were explored in the docudrama "An Adventure in Space and Time" as part of the 50th anniversary celebrations of "Doctor Who", which starred David Bradley as William Hartnell. Although Time Lords resemble humans, their physiology differs in
An Adventure in Space and Time from "The Daleks' Master Plan" using original actress Jean Marsh to play the increasingly aging Sara, and to use Super 8 footage of a recreation of the "Radio Times" publicity photo-shoot for "The Three Doctors", but the budget did not accommodate these ambitions. Principal photography for the film began in February 2013. Filming primarily took place at Wimbledon Studios in London, and the BBC Television Centre; it was the final drama to be recorded at the latter, which closed one month after filming concluded. Location filming took place on 17 February 2013, on Westminster Bridge in London. This involved replicas