The villain Lady Cassandra, a CGI creation voiced by actress Zoë Wanamaker, was developed for the episode. Executive producer Russell T Davies stated that Cassandra was inspired by drastic beauty treatments that had been taken by female celebrities, particularly inspired by the appearance of various female celebrities at the Oscars. He said, "It was horrific seeing those beautiful women reduced to sticks. Nicole Kidman struck me in particular. Nicole is one of the most beautiful women in the world. But she looks horrifying because she’s so thin. It’s like we’re killing these women in public. We watch while you die." Originally, Cassandra was intended to have collected pieces of human history, such as the Magna Carta and "Harry Potter and the Philosopher's Stone". The book still appears as a set piece, being contained in a glass cabinet decorating the Platform One hotel. Wanamaker reprised the role of Cassandra in the 2006 series' first episode, "New Earth".