Chief amongst these was the cast change that the serial brought. Mounting explored the departure of Carole Ann Ford and the arrival of Maureen O'Brien, revealing along the way that Denise Upson was also considered for the role of Vicki, and that Ford was herself welcoming to her replacement. The outstanding ratings of the serial are touched upon and it ends with Ray Barrett professing that he will have "out rated the Daleks" on his tombstone.