Roots: The Doctor paraphrases Humpty Dumpty ("all the king's horses and all the king's men"), the cabbie mentions Clint Eastwood and calls himself "the Cabbie with no name".
Intertextuality: The Doctor's comment "marvellous beings, most of them" is an adaptation of the Brigadier's occasional attribution to the Doctor - "splendid chaps, all of them." The regenerative substance lindos first appeared in Eric Saward's Target novelisation of The Twin Dilemma.
Double Entendres: "Wherever you lay your hat! This is my hat! There! I've laid it!"
Continuity: The Institute is one of several experimental stations initiated by the High Council into the feasibility of embedding time agents into the populations of 'lesser' species of interest to Gallifrey. The High Council have foreseen a time when other, less responsible species will have developed time-travel technology. Via the Institute's time-sensitive agents the Time Lords mean to monitor the development of these species and steer their scientific progress away from temporal achievement if necessary.
Species held in the Institute are hosts for complex artificial intelligences created within the Institute's block transfer generators. As a side-effect of the procedure is the erasing of the original mind, the Institute selects individuals who are about to die, to preserve the integrity of the Web of Time. A further side effect of the process lies in the nature of the artificial intelligences — as these are TARDIS consciousnesses they are too complex for humanoid minds — even those of Time Lords, and the hosts implanted have been driven mad from sensory deprivation. There are time-sensitives from almost fifty worlds in the Institute, including a hothouse-like wing for amphibians. Another Institute run by a Time Lord called Helgrim held Dalek mutants for their experiments — it ended disastrously and Daleks are forbidden from the experiments, although it is acknowledged that they would be of great use.
Feledrin are a gestalt or, as it is claimed, a compound species. Comprising of six smaller, clawed beings, their minds are linked by a telepathic matrix — they can function independently if necessary. They can survive exposure to space for several minutes. Other Feledrin held by the Institute were Warzitran, Korth and Vesera — at least one died as the Doctor arrived.
After regeneration a Time lord's brain can be scrambled 'for weeks'. Traces of Lindos in a Time Lord's system reveal recent regeneration.
Mel has read about phantom limb syndrome and had read the entire canon of Sherlock Holmes by the time she was nine.
The Doctor is detained in the Institute for three days. He claims not to need a space suit - he appears calmer and more lucid out in the open of space, as that's where he 'belongs'.
Links: TT capsules and the CIA were first mentioned in The Deadly Assassin. The Doctor's pitch-perfect imitation of Rigan is a skill previously shown by the Master in The Time Monster. The Doctor programs a holographic message for Mel via the TARDIS console (The Parting of the Ways). Mel's elephantine memory is mentioned again (The Ultimate Foe).
Location: Earth — England (probably London then) 1957, 2007
The Bottom Line: Ambitious, with several high concept elements (possibly a few too many — does the asteroid offer anything more than a cliffhanger?) and some good casting in Jennie Linden and Toby Longworth. Bonnie Langford's good, but Sylvester McCoy's mad routine wears after three episodes. It starts well, but suffers from performance and personnel changes, including a gestalt entity, flashbacks and a regeneration. There's an interesting story underneath it all, but perhaps an extra episode was needed to let it breathe.
Gallifrey and the Politics of Time Travel
Traditionally the rivals of Gallifrey in time travel technology were assumed to be the Daleks, with subsequent warmongering races (the Andromedans, Cybermen and Sontarans) mere pretenders through theft or acquisition. After The Apocalypse Element however Big Finish levelled the playing field, introducing new races already equipped with temporal tech (the Monan Host, whose world was created through a temporal accident), and later including one from the Doctor Who Monthly comic strip in the Warpsmiths of Phaidon. Order within the Vortex is maintained by a formal agreement between such temporal powers to protect lesser races from threat and enforce a moratorium on time-travel experiments.
By the time of Big Finish's Gallifrey series, which is assumed to follow from the events of Zagreus the Sunari and Nekkistan groups are also included, likewise featuring time travel as their raisen d'etre. Power blocs formed, with the Monans, Nekkistani, Unvoss, and Warpsmiths comprising a fragile coalition of temporal powers. In order to counteract this President Romanadvoratrelundar initiates the creation of a 'temporal bubble world' called Gryben which attracts unauthorised timeships to it and acts as a vetting centre for those cultures petitioning to join the temporal race — those rejected and unable to return home are detained indefinitely on the planet, essentially turning Gryben into a refugee centre and massing point for temporal tech dealers and a resistance group calling itself Free Time (other races within Free Time variously include Gallifreyans, humans, and Yevnons alongside the Monan Host). Free Time's philosophy that no one power should have authority over time and that it belonged to everyone falls foul of Gallifrey itself, which then employs the Celestial Intervention Agency (and its Vortex Ops units) to monitor the group's activities.
Such is the state of politics that inform some of the background detail of Big Finish's stories of 2005; in Medicinal Purposes antagonist Knox has acquired a TARDIS from a Nekkistani dealer on Gryben, and it is a vessel of Nekkistan origin which is retconned into the beginning of Storm Warning by the events of Terror Firma. It could be assumed that the rising tensions between Gallifrey and its rivals (not excluding the Daleks of course) and foresight of increased access to temporal technology provokes Gallifrey to conduct the experiments referred to in Unregenerate!
The finale (one resists the urge to call it a conclusion) of the Gallifrey series sees temporal catastrophe envelop Gallifrey, and the not-refuted suggestion by fans that the Time Lords' oldest rivals, the Daleks, eventually exploit this instability. This loosely accommodates the suggested Gallifrey/ Dalek Time War referred to in the new TV series, and to date Big Finish seem happy to leave it there.