Every episode of Doctor Who has much more than meets the eye so I like to put together a little post exploring links to the past and other things you might not have known about!
WARNING: Contains Spoilers
The episode is almost entirely set in Coal Hill School, a location that has appeared numerous times in Doctor Who. In the very first episode of Doctor Who in 1963, An Unearthly Child, the Doctor’s Granddaughter Susan went to school there and teachers Ian Chesterton and Barbara Wright became the first companions.
The Doctor also visited the school in Remembrance of the Daleks (1988)when the then headmaster assumed he was applying for the vacant position of caretaker! Since The Day of the Doctor (2013) Clara has been an English teacher at the school.
The Doctor says that “artron emissions” may have brought the Blitzer to the area. Artron emissions are an output of time travel and with the Doctor visiting the area so often it is no surprise there are high emissions in the area.
The term “artron emissions” was first used back in Fourth Doctor story The Deadly Assassin (1976) and has been used numerous times since, like when Kate Stewart used artron emissions to rack the Doctor in The Power of Three (2012).
Jimmy Vee plays the Blitzer, making his fourth appearance in Doctor Who. He previously played the Moxx of Balhoon in The End of the World (2005), the Space Pig in Aliens of London (also 2005) and Bannakaffalatta in Voyage of the Damned (2007).
The Twelfth Doctor mentions River Song for the first time in this episode. He also suggests taking Clara to the London Frost Fairs, a location he once took River (and Stevie Wonder).
There’s a great play on the troupe of the Doctor having met famous people when he mentions he knows the date Jane Austen wrote Pride and Prejudice by reading the book, rather than having been there as Clara expects.
Danny Pink is the second maths teacher who was once a soldier the Doctor has met. His old friend Brigadier Lethbridge-Stewart became a maths teacher at Brendon Public School after leaving UNIT.
The Doctor once again uses the pseudonym John Smith here. He first used the name in 1968’s The Wheel in Space and has used it countless times since- like when he last went undercover in a school as a physics teacher in School Reunion (2006).
We see another area of Heaven at the end of the episode and an “employee” of Heaven called Seb played by Chris Addison. Seb says Heaven can be called “the Nethersphere”. When first announced, Michelle Gomez’s character, referred to as Missy in the show, was called “the Gatekeeper of the Nethersphere”.