OK, super random thought - but what if The Devil's Chord was not originally intended to be the 3rd episode of the season (as there is, per dialogue, a 6-month gap between the end of Space Babies and TDC) but that the season was rearranged after filming to air TDC on the same day as Eurovision?
So, we may, in fact, be seeing the season out of order. It would make some of Ruby's dialogue in TDC make a bit more sense. #DoctorWho
