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Knock Knock: The Fact File

Knock Knock is the first Doctor Who adventure to be available with a binaural, 360 soundscape. This version was released on BBC iPlayer shortly after the ‘standard’ episode finished airing on BBC One. Find out more about the binaural process here.

Sally Sparrow in 'Scooby Doo's house' in Blink

The episode begins with a literal ‘knock knock’ as Shireen uses the knocker on Bill’s door.

There are several ‘pop culture’ references in Knock Knock… Indiana Jones and I’m a Celebrity, Get Me Out of Here! are both mentioned and Shireen calls the building, ‘This freaky Scooby Doo house!’ The last of these brings to mind Blink, where Larry called Wester Drumlins (the site of a memorable Weeping Angels attack), ‘Scooby Doo’s house.’ Talking of which, exterior scenes featuring the Landlord’s home in Knock Knock were shot in the same location in Newport, south Wales, as the Wester Drumlins scenes in Blink.

The Doctor declares, ‘Sleep is for tortoises!’ He made the same comment in the 1977 story, The Talons of Weng-Chiang.

When the housemates are trying to scare each other about the strange noises in their new place, Paul says, ‘Maybe it’s a little doll that’s come to life…’ and Shireen adds, ‘Or a massive freaky spider!’ This evokes several scenes from 1970s Doctor Who, such as the moment in Terror of the Autons where a plastic toy doll, activated by heat, seems to ‘come alive’ and attacks the unfortunate John Farrel. The arachnid allusion conjures up visions of the Third Doctor’s swansong which featured a Spider Queen, known as ‘the Great One’, who was the size of a cathedral and desperate to rule the entire universe, making her – you guessed it – a massive, freaky spider!

The Third Doctor and Sarah Jane in Planet of the Spiders

The Great One could also recreate the voices of other beings. She put together a few lines of Pop Goes the Weasel, delivered as though sung by the Doctor and Sarah Jane Smith. At the end of Knock Knock we hear an instrumental version of the same ditty.

And whoever or whatever is in the Vault apparently shares the Doctor’s penchant for Beethoven. The music we initially hear being played on the piano is his Bagatelle No. 25, better known as Für Elise. The name ‘Elise’ is a form of ‘Elizabeth’ which can also be shortened to Eliza…

‘Reminds me of Quincy Jones. I stepped in for him once…’ Quincy Delight Jones, Jr. (born March 14, 1933), is a celebrated American record producer, actor, conductor, arranger, composer, musician, and instrumentalist. He was a close friend of Frank Sinatra, the singer/actor whose hunting lodge the Doctor hung out in with Father Christmas in 1952.

When the Doctor mentions a ‘Klarj neon death voc bot’ he’s possibly discussing a version of the Voc robots known as ‘The Robots of Death’ who appeared in a story of that name in 1977.

Bill says to her mum, ‘Stop it! There’s no living puddles or weird robots… big fish!’ She’s clearly talking about events seen in The Pilot and Smile with the ‘big fish’ almost certainly a reference to the Thames ‘snake’ that appeared in Thin Ice.

The Seventh Doctor and Ace, who never quite made it to the Great Wall of China…

The Doctor calls the ‘space lice’ Dryads. In Greek mythology dryads were tree spirits, also known as ‘tree nymphs’. In most stories, dryads were presented as shy and peaceful, never further than a few steps away from the tree they associated with.

‘Mine went greypacking on the Great Wall of China with his boyfriend,’ Harry reveals, ‘but they got arrested for trying to steal a bit…’ This isn’t the first time the famous wall has been mentioned in Doctor Who. In the show’s 30th Anniversary special, Dimensions in Time, the Doctor is trying to take Ace to the Great Wall of China, but it’s strongly hinted the TARDIS has been re-routed to London by the villainous Rani!