The character of Jenny was originally intended to be Susan's replacement although this was halted over uncertainty about the future of the series.
This episode takes place in London in the 2160s.
This episode was watched by 12.4 million viewers on its original transmission.
One of the original Dalek props that makes a return appearance, takes on 3 individual roles in this story, first on location it was a standard Silver and Blue drone and is seen in the Location footage, then for the studio session for the second episode it was modified into the Saucer Pilot (Incorrectly identified as the supreme) now sporting a mixture of Silver, Black and Blue, then for Episode 3 on wards in the studio it became the Supreme Dalek the wholly black and blue dalek.
Baker was originally named Roger Krish.