There are are more than a few conscious nods to classic Doctor Who within the story of "Hide," not least the fact that the Doctor meets a fellow scientist and his glamorous assistant (and even mentions that this is what they called companions back in 1974. But it is also a heartwarming tale of love, in which the Doctor plays matchmaker for one couple and enables a second to get back together.

Here are a few things to keep an eye out for, the next time you watch:

(The episode is available on iTunes and Amazon.)

Having been invited to write his first story for Doctor Who, Neil Cross (creator of Luther) drew inspiration from two stories by Nigel Kneale that had been televised in his youth. The storyline of a scientific investigation of a haunted house echoed his TV play "The Stone Tape," and for a while Neil wanted the Doctor to meet Bernard Quatermass, one of the principal characters in Kneale's The Quatermass Experiment. This proved to be impossible for copyright reasons.

The first draft of the script was entitled “Phantoms Of The Hex” and included the idea that the pocket dimension in which Hila was trapped was a prison, and home to a renegade Time Lord called the Revenant of Anathenon - also known in Gallifreyan legend as the Lost Lord. His plan was to tempt the Doctor into his realm, kill him and feed upon his, so he could make the journey back to the universe. As a name for the pocket dimension, the Hex would remain in the script, also known at one point as "The Hider in the House," until the story came to be edited.

Neil Cross named the stately home in which this story takes place Caliburn House after King Arthur's sword. In the version of Arthurian legend told in the 12th century by Geoffrey of Monmouth, the sword we now know as Excalibur was called Caliburnus, which was translated, in Chrétien de Troyes' late 12th-century Perceval (written in Old French) to Escalibor.

Clara uses the fine old British slang term doss, as she mockingly says to Professor Palmer: "Sorry. You went to the bank and said, you know that gigantic old haunted house on the moors? The one the dossers are too scared to doss in? The one the birds are too scared to fly over? And then you said, I'd like to buy it, please, with my money."

It's a word meaning to sleep where you can, with the inference that if you have to doss, you're not in a position to be too choosy. Changing it from a verb to a noun adds an edge of judgement, so someone who has to doss down becomes a dosser, and indeed homeless shelters did acquire the nickname doss-houses, implying that these were places that you would not wish to stay in if you had the choice.

https://www.youtube.com/watch?v=-pp_2B1J6D0

The Doctor brings out his blue crystal from Metebelis III to help amplify Emma's powers. This first appeared in the hands of the Third Doctor, in the eco-horror story "The Green Death." He later visited Metebelis III in "Planet of the Spiders" although in both occasions, the Third Doctor pronounced it "Meh-TEB-eh-liss", rather than "Meta-BEE-liss". The Eleventh Doctor clearly prefers the latter pronunciation.

He also demands some Kendal Mint Cake, referring to a popular sweet made from sugar, glucose, water and peppermint oil, and a source of energy for mountain climbers and hikers. Apart from being a sensible snack to keep in your pocket in trying times, the addition of the Kendal Mint Cake to the Doctor's list of requirements may act as a balance for Clara saying that Carlisle is the "opposite of bliss". Carlisle is the county town of Cumbria, while Kendal is that county's second city.

https://www.youtube.com/watch?v=5P0eCF6Hq-c

The Doctor describes Professor Palmer as being one of the "Baker Street Irregulars," which is not a reference to the street children who run an informal intelligence network for Sherlock Holmes in Sir Arthur Conan Doyle's stories. He was actually talking about the Special Operations Executive, a team set up by Winston Churchill during the Second World War to conduct espionage, sabotage and reconnaissance in occupied Europe and aid local resistance forces. Despite emplying 13,000 people, the SOE was kept secret, but not so secret as to avoid nicknames. They were known as "Churchill's Secret Army" or the "Ministry of Ungentlemanly Warfare", and acquired the nickname "Baker Street Irregulars" as their headquarters was situated at 64, Baker Street, London.

The sequence in which Clara struggles to gain entry to the TARDIS in order to go and fetch the Doctor from the pocket dimension is similar to an argument between companion and time machine in the audio drama "Zagreus." In that tale, Charlotte Pollard struggles with a jealous TARDIS, and in "The Next Life", she also refers to the Doctor's ship as a "cow."

Clara is unlucky not to have found a place to put her wet umbrella in the TARDIS, as the Doctor's First, Second, Fourth, Fifth and Seventh incarnations all had visible umbrella stands, and there's a hat stand clearly on display in the console rooms of the Fifth, Ninth and Tenth Doctors, and even the Eleventh, before he redecorated.

On realizing the monster he's been running from is actually lonely, the Doctor says "birds do it, bees do it, even educated fleas do it," quoting from the Cole Porter song "Let's Do It (Let's Fall in Love)", one of the defining songs of the 20th century, and a notable addition to the Great American Songbook:

https://www.youtube.com/watch?v=z8NtdS98IRI

NEXT: "The Crimson Horror"

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