Roots: La Morte de Arthur. Emfil recalls Marvel Comics villain the Collector. There are references to Heidi, Star Wars (light sabres), Michael Douglas and Falling Down, Hamlet, Alice in Wonderland, Indiana Jones, and Snow White and the Seven Dwarves.
Dialogue Triumphs: "Don't underestimate peace, my lord. You'll miss it when it's gone."
"If we are busy chasing a mirage, we cannot waste ourselves waging war, can we?"
"It's usually ordinary people who get hurt when lords and generals start a war with each other."
Continuity: The people of Varuz once had advanced technology, of which remnants remain, and ruled their entire world. Their empire was apparently tyrannical. They had space travel, although the Doctor doubts that they ever travelled outside of their own star system. They have lost the secret of their technology, which drew power from the land and ultimately caused it to wither. Their planet has at least one ocean.
The Glamour is an object so entrancing and so powerful that people will kill in order to have it. It can change its shape in order to resemble the heart's desire of whoever sees it [see Deep Time]. Lancelot is actually the Glamour. The knights he leads in the quest for the Glamour are originally from Earth and have been kept alive for centuries by its power.
Emfil is a humanoid alien collector.
Clara dons a deep red gown with a full skirt, bejewelled orange sleeves, and rich brocade worked into the bodice. She drinks a chocolatey drink with Guena.
Links: The Doctor refers to the events of Battlefield.
Location: The city-state of Varuz on an unnamed planet.
The Bottom Line: "Where there's a throne, there's a plot." A lyrical fantasy saga, with poetic prose and some excellent supporting characters. McCormack writes both the Doctor and Clara very well, and achieves some excellent world-building without overly relying on the usual sci-fi tropes. A triumph.