The Castle is a radio series first broadcast in 2007. Described as "a comedy set in the filth, grime, stench and brutality of the Middle Ages, with some nice music", it is a comedy set in an uncertain period in the Middle Ages, at the castle of Sir John Woodstock, a meek and mild mannered widower who lives with his daughter Anne (who refuses all attempts to marry her off despite approaching the dreadful age of eighteen, his son Henry (who begins to speak like a Gangsta Rapper as the series goes on) and Anne's friend Charlotte, who is staying over whilst her parents are in Europe (and blatantly having affairs).
Other major characters include:
- Castle Woodstock staff Thomas the inventor and Sam Tree the dimwitted but handsome peasant (eventually replaced by Merlin, a wizard handyman)
- ... and neighbors Sir William de Warrenne (Knight Errant, Scourge of the Levant, increasingly desperate suitor to Anne) and Cardinal Duncan, a closeted homosexual and advisor to Sir William.
- Anachronism Stew: Deliberately invoked, with characters, headlines and events being obvious references to the present day, for example the aggressive chef Sir Gordon De Ramsay and the Italian knight Antonio Soprano. Sometimes they don't bother to hide it at all and reference the figure or event directly.
- In additional, all of the music is modern pop music performed on lutes, recorders and other contemporary instruments.
- Bait-and-Switch: Thomas' inventions all resemble modern devices, . Sir John will then ask for what they would call the device, prompting a stupid name in place of Sir John's reasonable one.
- Blue-Collar Warlock: Merlin is a wizard, but spends most of his time doing handyman jobs like putting up shelves.
- Catchphrase Everytime Lady Charlotte sees Sir William she remarks "Cool codpiece!" prompting his response on the design, usually with a reference to a modern designer.
- Constant complainer Jedediah Wainwright interrupts every proposal at the town meeting with "That's outrageous!" which is followed by "Shut up Wainwright!" from the crowd.
- Courtly Love: Despite being a knight errant, Sir William has absolutely no idea how to do this.
- Double Entendre: The source of about half the jokes.
- Dumb Blonde: Averted, blonde Lady Anne is the bright one, her brunette friend Charlotte is The Ditz - though this varies from episode to episode.
- Expy: With his Failure Knight tendencies, Miles Gloriosus-esque behaviour and snarky assistant, Sir William comes across as something of a 12th/13th century Zapp Brannigan.
- Fake Ultimate Hero: The Woodstocks are eagerly await the arrival of Sir William De Warenne. Then they meet him.
- Giver of Lame Names: Thomas, in contrast to Sir John.Sir John: What do you call this thing that rockets up?Thomas: The sky stick.
- Moral Guardians: Jedediah Wainwright, who objects to everything at town meetings with the declaration "that's outrageous!".
- Mr. Fanservice: Sam Tree, the dim odd jobs man who performs his duties with no shirt on, to Anne and Charlotte's delight. When Sam disappears on a crudely constructed rocket, Anne's main proviso for a replacement is that he works with his shirt off.
- Name's the Same: There was a real life Sir William de Warrene.
- Only Sane Man: Sir John and Duncan in their respective ways.
- The Other Darrin: Lady Anne is Susan Earl in Series One, Montserrat Lombard in Series Two and Three and Martha Howe-Douglas in Series Four.
- Sam Tree is Toby Ross-Bryant in the first series but is replaced by Steven Kynman later on.
- The Power of Lust: On more than one occasion Anne and Charlotte use this to get their own way. Notably Charlotte has her breasts artificially enhanced to cause a distraction.
- Really Gets Around: Some of Charlotte's comments certainly give off this impression...
- Stealth Pun: The Merk Inn.
- Take That!: A number of encounters with the modern-day parodies end this way.
- Transparent Closet: Cardinal Duncan, though this generally flies over other characters' heads, largely because he is Surrounded by Idiots.
- Virgin Power: Merlin loses some of the stronger elements of his magic when he sleeps with Charlotte.