- Complete Monster: The Collector is a Usurian representative of the Company, who moved humanity's population from the exhausted Earth to first Mars and then Pluto, setting up a series of artificial suns. The Collector has created a brutal dystopia in which the humans are effectively slaves, where every aspect of their lives, including breathing, are taxed, often creating a vicious cycle where they are forced to work extra shifts to pay their debts, increasing their debts through dependence on stimulant drugs, until they are Driven to Suicide. Ordinary citizens are forbidden to see the sun, rebellion is kept in check by lacing the atmosphere with a chemical that keeps everyone in a constant state of fear, and crimes are punished by constant torture at "correction centers". The Collector plans to ultimately abandon the humans when they cease to be profitable, leaving them all to die when the suns run out of fuel. He sentences Leela to execution by boiling alive, gleefully noting "This is the point where I get a real sense of job satisfaction". Ordering mandatory time off so that the workers have to listen to her screams, then orders them to work unpaid overtime to make up for the drop in production. He treats even his elite with contempt, bullying his underling, Hade, and using his personal guard as a Human Shield during a rebellion. To end the rebellion he attempts to gas the city, killing even those still loyal to him.
- Genius Bonus: The Doctor at one point when offered something to eat asks "Rubus idaeus?" and is told, "No, raspberry leaves". Rubus idaeus is the scientific name for the red raspberry.
- Retroactive Recognition: Goudry is Vila Restal. In fact, director Pennant Roberts suggested Michael Keating for that role having worked with him on this serial.
- Some Anvils Need to Be Dropped: The Doctor points out how the Usurian economic enslavement methods - driving entire races into economic ruin and despair - are as bad as wars.
- Values Resonance: The story combines this with Broken Aesop. In 1978 it was a right-wing allegory about how taxation is evil, but in the late 00s and 10s, it's a left-wing Occupy allegory about how forcing the tax burden on the poor to benefit big corporations is evil. Complete with a gas that makes everyone afraid being pumped into everyone's houses - an allegory for news media, which has become much more omnipresent and sensationalist since 1978.
- What Do You Mean, It's Not Political?: It's well known that the story is about the evils of taxation and written by a Thatcher supporter, but, since the actual story presents the issue more as 'untouchable mega-corporations and corrupt bankers have bought out the government and are draining money out of the poorest to boost their own profits while keeping the population constantly afraid via media to distract them', modern critics tend to read it as a satire on the evils of privatization, or Occupy-style anti-capitalist. Privatization was just around the corner in 1977, and the Occupy movement was 35 years away. Is it more likely that Robert Holmes was secretly hard-left and able to see the future, or that he was ramping up the setting's systemic injustice to the point he accidentally broke his own right-wing aesop?
YMMV / Doctor Who S15 E4 "The Sun Makers"