The Witch’s Familiar: The Fact File
The read through for The Witch’s Familiar took place on Monday, 9 February, 2015, in Cardiff. Filming for the episode took place in Wales with an overseas shoot in Tenerife – the Canary Island that doubles for Skaro.

The footage that can be seen on the screen in Davros’ sanctum early on in the episode is from Genesis of the Daleks, the 1975 six-parter that’s heavily referenced throughout this adventure.
In episode 5 of Genesis of the Daleks, Davros becomes enthused by a concept suggested by the Doctor. ‘To hold in my hand a capsule that contains such power [to destroy all other forms of life], to know that life and death on such a scale was my choice. To know that the tiny pressure on my thumb, enough to break the glass, would end everything… Yes, I would do it! That power would set me up above the gods!’ This line is brought to mind during this adventure when Davros says, ‘Imagine… To hold in your hand the heartbeat of every Dalek on Skaro… They send me life. Is it beyond the wit of a Time Lord to send them death… Such slaughter… Are you ready to be a god?’
It’s a Special Weapons Dalek! First seen in 1988’s Remembrance of the Daleks, one was glimpsed more recently in the Eleventh Doctor episode, Asylum of the Daleks.
We hear the distinctive Dalek ‘heartbeat’ sound several times in this episode. It’s featured in many previous stories including Destiny of the Daleks and Victory of the Daleks and was originally used in the very first Dalek adventure. In fact we heard the Dalek ‘heartbeat’ before we heard their familiar battle cry of ‘Exterminate!’

Another familiar Dalek line – ‘My vision is impaired! I cannot see!’ – makes welcome return in The Witch’s Familiar. The squawk of distress was first heard in the Third Doctor adventure, Planet of the Daleks, back in 1973.
‘The only other chair on Skaro…’ Daleks aren’t big on making their cities accommodating for strangers! In the very first Dalek adventure, one of the Doctor’s companions, Barbara, tried to describe the Daleks’ world and noted, ‘Well, there wasn't any furniture, now I come to think about it…’
There are more echoes of the first Dalek story… In that adventure another of the Time Lord’s companions, Ian, squeezes inside a Dalek’s casing in order to attempt an escape. And the Doctor concealed himself in what appeared to be a Dalek’s shell during episode 2 of The Space Museum.
The TARDIS defence mechanism known as the Hostile Action Displacement System, or HADS for short, was first used in the Second Doctor adventure The Krotons and more recently in 2013’s Cold War. It kicks in when the time machine is in danger and moves it to a safer location. The mechanism that operates here is slightly different – the craft’s Hostile Action Dispersal System redistributes the TARDIS although the Doctor is easily able to reassemble it with ‘a quick blast’ of his sonic!

When Davros asks, ‘Am I good man?’ he’s repeating the question the Doctor put to Clara in the previous season’s story, Into the Dalek.
‘I’m over screwdrivers…’ The Doctor’s sonic screwdriver has been spoiling the line of his jacket since the 1968 story, Fury from the Deep. One version was destroyed in 1982’s The Visitation leaving the Time Lord apparently scewdriverless until the Seventh Doctor’s final adventure in 1996. Different Doctors have used different-looking versions of the device, a fact directly referenced in The Day of the Doctor where it served as a metaphor for his changing appearance. (‘Same software… different case!’)
The Doctor’s ‘sonic shades’ are the latest in a long line of sound-based devices to feature in the Doctor Who universe. Others include Sarah Jane’s ‘sonic lipstick’, Captain Jack's sonic blaster and, of course, the sonic screwdriver. The Doctor also used a sonic lance in 1985's Attack of the Cybermen, whilst the Ice Warriors came armed with sonic canons and in Partners in Crime the ill-fated Miss Foster carried a sonic pen.