Roots: The Last Emperor (?), Shogun (?) Ten Little Indians, Japanese ghost stories ('hungry ghosts'). The closing of Imperial Draconia recalls the Sakoku policy of Tokugawa period Japan.
Goofs: There seems to be some confusion about when the Doctor visited the Red Emperor and the Space Plague arrived - the Doctor says it was sixty years ago, while the Queen claims it was fifty.
Mila-Charley is familiar with the suffragettes and Emmeline Panckhurst (one of Charley's memories, unless this was at one time a topic of discussion in the TARDIS), yet seems unfamiliar with the pyramids of Giza and their function, with which she ought to have been familiar after The Daleks' Masterplan and Pyramids of Mars at least.
Double Entendres: "My ship... I'm afraid it got stuck in your works"
"All the best tyrants have a twinkle"
Continuity: The Draconian Empire lasted for at least a thousand years and encompassed dozens of world, including among those it lost Drovia, Patares, Aphoria and Teng. Named places include the Sitengi province, a poorer area which is the home of the fish catcher Jen/Gomori. Animals mentioned as being native to Draconia (or possible equivalents if the TARDIS' translation circuits must be considered) include horses, dogs, eels and snakes - which collequially appear to be regarded as low and despicable creatures. The first Draconian Emperor was the White Emperor, known for his savagery and for rising to great power on the battlefield. It is said that he conquered 52 worlds, and afterward Draconia's sun ran purple with blood [judging by this it might be inferred that these worlds were part of a pre-Imperial Draconian realm, although the Queen also mentions "warm-blooded" ambassadors visiting the Red Emperor's court]. Like all emperors after him he was characterised by a distinct colour, his successors including gold, green, pearl grey, blood purple, dusk blue, and red, the fifteenth and most recent Emperor. The Celestial calendar includes the year of the star and the urn.
The Red Emperor assumed his throne at an early age (the Doctor likens it to Charley's age - so perhaps nineteen or twenty) "sixty years ago" (see: Goofs) - his death occurred in the Eightieth year of the Blood - relatively speaking 150 years before the Doctor actually opens the summons to the Imperial court. During the Red Emperor's reign and in the Seventieth Year of the Serpent the Doctor visited Draconia (see: Untelevised Adventures), became a noble and the Emperor's advisor and ultimately suggested an extreme measure to protect the Empire from the then-rumoured Great Space Plague, a policy of extreme isolation on point of death that cut Draconia off from its neighbours and nearly ruined the Empire. For this action the Red Emperor, hitherto regarded for his sense of humour, became a controversial figure and the Doctor something of a scandal, branded a 'serpent' in some quarters. Nevertheless, presumably under the Doctor's guidance the Emperor insisted that all of his subjects be given the eventual antidote to the Plague rather than selected nobles, so the long-term survival of the Draconian race is also attributable to him.
Imperial Heaven is a necropolis comprised of a fleet of fifteen 'tomb ships' floating in orbit above Draconia, each belonging to a deceased emperor. Each emperor occupies a single tomb ship, the craft's outer features reflecting the architectural style of their time. Within, the tomb ships are austere complexes with marble floors and fusuma-like paper interior walls. Each tomb ship contains the treasures of that emperor, plus a full half set (i.e. one 'army') of sazou pieces under that emperor's psychic command, coloured after the emperor to which they belong, but otherwise identical; they fly from tomb ship to tomb ship as the Undying Emperors while away eternity with their games, or 'painting' their memories, thoughts and messages to one another on the paper walls of their resting places. At the centre of the necroplis is the Temple of the Spilling Sun, a room of literally bottled energy and the power source of all of the tomb ships. Embalming is part of the funerary ceremony for each emperor, followed by three days of contemplation in honour of the deceased, and officiated over by the dragon-masked Tombkeepers, a priestly profession open only to Draconian females. After this time the decree of succession is read by the Tombkeeper and the new emperor anointed (the Red Emperor's son seems to have fancied himself in the colour black). Lineage tends to be patrilineal, although it may be inferred from the Queen that the Emperor might have many consorts, provoking competition between mates (to the point of infanticide) in order to produce the next heir - in this instance it is revealed that the young Prince has younger male siblings. Despite this ceremony it is apparent that all of the Undying Emperors are in fact not dead, merely kept in a state of slowed metabolism in a form of life support built into their funerary throne by the Priests.
Sazou is a form of Draconian chess played between armies of fifteen pieces, including the Snake Warrior, Acolyte, Mace Bearer, Siege Engine, Redoubt, Warrior Captain, Boat Rider, Broken Tower, Palace Gate and more than one Charger which, similar to the knight in modern chess, must move sideways and forward in one turn. Traditionally these pieces are small and carved, some even being so small they can be carried in the sleeves of a noble's robe. On other occasions they may be 'played' by real people, and life-sized origami pieces intricately folded from great single sheets of infinitesimally sharp fractal paper decorate the tombs of the Undying Emperors.
The TARDIS has a message recovery system (an 'In Tray') which contains 8640 messages, many of which the Doctor regards as spam.
The Doctor learned the practice of "passive wakefulness" (sleeping with one's eyes open) from a Subeckian shaman - although as the shaman was a reptile it came rather more naturally to him. Lord Salisbury apparently loaned the Doctor his [blue] morning coat; the Doctor later changes into the green silk and bronze shoulder plates seen in Frontier in Space, which he regards as "so last dynasty" [whatever else, the style must have returned for it to be worn again many years later].
Location: Imperial Heaven, above Draconia, the 80th year of the Blood. The 31st century (if we take a 'thousand years' to have begun mid-21st century)
Links: Frontier in Space, Patient Zero
Untelevised Adventures: It was the same Red Emperor the [First?] Doctor met and who encouraged him to Draconia's policy of isolation some sixty years previously. He also played sazou against the Emperor, being the only person to beat him, and only saving his own life by his intervention with the Space Plague. In this game the pieces were played by red-robed nobles of the court across a board set in the palace gardens. There the Doctor also met the future Queen - then a child of twelve who wore a necklace made from her own eggshell and bit the Doctor's hand, throwing the TARDIS key into a fountain when his Charger challenged her adopted piece, the Red Acolyte. In the court he also met Tagoya Azul, the son of the Captain of the Imperial Bodyguard, to whom he gave a gold sovereign with the head of Charles I on it. As rumours of the Great Space Plague grew the Emperor's court emptied, with many off-world ambassadors fleeing for their home planets.
The Bottom Line: "Other lands, lands over the horizon may as well not exist. The whole world could be made up for all I know."
Under-rated. Marc Platt's imaginative interpretation of Draconian society (hardly the most subtle allegory of Doctor Who's normally allegorical alien races) adds to one of the more background cultures of the series, finding a place for females and a reliably visual representation of their afterlife. There's little for Mila-Charley to do, and perhaps this is the story's weakness if you're looking for a proper 'middle section' to the Patient Zero trilogy, but there's enough to remind the listener that all is not as it should be in the TARDIS.