Christine Gascoine (Siobhan Redmond) is a villainess from New Tricks' third season opener, "Lady's Pleasure" (airdate 17 April 2006). She is a schoolteacher and a friend of Nancy Murray and Josephine Sargent; the former of whom was killed five years prior to the episode's events.
UCOS' investigation into Nancy Murray's death revealed that she, Christine, and Josephine were all connected to Larry Bevan, a rugby player who also worked as a prostitute. Josephine had a one-night stand with Larry, and she decided to have her both of her friends experience Larry for themselves. Nancy, who was married to Stephen Murray, was having a months long affair with Larry at the time. Regarding Christine, she began to fall in love with Larry, as she stopped paying him for sex and only did so to help him out, as she hoped that he would give up his profession.
But when Larry's relationship with Nancy continued, Christine resorted to blackmailing Nancy by leaking racy photos of Larry and Nancy from the former's website, while also sending notes to Nancy where she threatens her job and labeled Nancy as a "whore." When her villainous scheme failed, Christine went to Nancy and pleaded with her to give up Larry so she could be with him, only for Nancy to lash out at Christine in response. On the day in question, September 26, 2001, Christine met Nancy in front of a wine bar, but was shocked to see that Nancy had become a villainous madwoman bent on killing not only Christine, but herself as well. Christine saw Nancy speeding towards her in her car, and escaped Nancy's attempt, leaving only the deranged Nancy to be killed on impact.
In the episode, Christine's encounter with DSI Sandra Pullman had her claim that the allegations regarding Nancy cheating on Stephen were lies, as the couple was planning a vacation in the Seychelles. However, it was revealed that the trip was canceled three days before Nancy's death, with Sandra believing that Stephen killed her and holding that belief since that day, until a test run revealed the truth. Photos of Christine on Larry's site ended up revealing her as the blackmailer, and in the episode's climax, Christine confessed to blackmailing Nancy, In addition, Christine expressed horror over Nancy's sudden heel turn, voicing her shock over the fact that the woman who Christine considered a friend had died trying to kill her. After she witnessed Larry's true colors in another room, Christine was officially arrested and charged with blackmail.