Inspirations: The Unicorn and the Wasp

The Unicorn and the Wasp is this season's celebrity historical. This time it is the 1920's, and a meeting with the "Queen of Crime" Agatha Christie (1890 - 1976).

Like the previous series' celebrity historical - The Shakespeare Code - it is written by Gareth Roberts, and like that story he basically uses the writings of the celebrity to form the basis for his plot. He also employs lots of the celebrity's titles or well known sayings in the dialogue.

In this episode, Roberts uses quite a few of Christie's many, many book titles. These include:

• Sparkling Cyanide
• Dead Man's Folly
• Cat Among The Pigeons
• Nemesis
• The Secret Adversary
• N or M? (The scrap of paper in the fireplace)
• Why Didn't They Ask Evans? (The professor says: "Why didn't they ask... Heavens!")
• They Do It With Mirrors
• Appointment With Death
• Cards on the Table
• Yellow Iris (There is a vase next to the Doctor when he is poisoned)
• Crooked House
• Endless Night
• Taken at the Flood
• The Moving Finger
• Death Comes As The End
• Murder At The Vicarage ("Murder at the vicar's rage..." says the Doctor).

Other book titles are mentioned specifically - Murder on the Orient Express is mentioned by Donna, unaware that Agatha hasn't written it yet. Lady Eddison reads a copy of The Murder of Roger Ackroyd, and it is this which triggers the entire chain of events. 

The Colonel pretending to be disabled, and the jewel thief posing as a house guest, are both plot points lifted from After the Funeral.

The Doctor is The Man in the Brown Suit.

Roberts was inspired to have a giant wasp as the monster in this by the cover of the 1957 Fontana paperback edition of Death in the Clouds. This novel involves a blackmailer being murdered on a flight from Paris to London. An injection of poison has been sued, initially mistaken for a wasp sting. The cover depicts the wasp in close up - making it look like a gigantic insect is threatening the aeroplane:

The Doctor shows Donna a facsimile copy at the end of the episode - one published in the year 5 Billion (suggesting it comes from New Earth).

Some of the incidents are lifted from And Then There Were None. This was previously given a title which is quite unacceptable today. The draft script was going to allude to this:

DONNA: "It's like Ten Little -"

DOCTOR: "Niggles aside..." 

The episode is set in early December 1926 (despite the weather seen on screen) as this was when Christie famously disappeared from her home. Her car was found at Newlands Corner in Surrey, and it was at first feared that she had drowned herself in the Silent Pool - a nearby beauty spot. She was found 11 days later at a spa hotel in Harrogate, claiming loss of memory. She was in the middle of an acrimonious split from her first husband at the time. She elected not to mention the incident at all in her autobiography. Theories include a nervous breakdown, or a deliberate attempt to embarrass her husband. The general public suspected a publicity stunt for her books.

Sherlock Holmes is referenced in that Donna thinks of detectives as going around with a big magnifying glass - an image usually associated with Holmes.

She speaks to Agatha about Miss Marple - not realising that she had not been created yet. Christie's detective in the early years was Hercules Poirot only.

She also gets a bit confused about whether or not Noddy is a real character. Noddy was the 1949 creation of Enid Blyton.

The other big inspiration is the boardgame Cluedo - itself inspired by the works of Christie. In this, the players have to guess the identity of a murderer, as well as the murder weapon used and the location in the country house where the crime took place - e.g. Professor Plum, with the lead pipe, in the library.

This is the very crime seen in the opening section of the episode, as Professor Peach is killed in this fashion, in the same location.

Other characters in the episode also mirror Cluedo characters:

• Robina Redmond = Miss Scarlet
• Clemency Eddison = Mrs Peacock
• Colonel Curbishley = Colonel Mustard
• Miss Chandrakala = Miss White
• Rev. Golightly = Rev. Green

The Doctor has a store of items in the TARDIS catalogued alphabetically, with the paperback novel under "C" for Christie. This also contains the Carrionite crystal ball prison (The Shakespeare Code) and a Cybus Cyberman chest plate.

The Doctor has "kissed" all of his female companions since 2005, and here Donna kisses him as a way of shocking him, to help expel the toxin.

The first idea was to have the story set in the 1960's, with an older Christie acting like her Miss Marple character, before settling on the 1920's which was visually more interesting. 

David Tennant had starred with Fenella Woolgar in a movie about 1920's high society - Bright Young Things, directed by Stephen Fry and based on the work of Evelyn Waugh. Woolgar had form with Christie, having previously featured in two episodes of the ITV series Agatha Christie's Poirot.