Elizabeth Clayton (Susannah Harker) is the main villainess from "Old School Ties," episode 9.02 of New Tricks (airdate 3 September 2012). She is the headmistress of Peregrine Manor, a prestigious private school.
One of the teachers was Jason Bowe, who taught PE until his disappearance in June 2007. His remains were uncovered in the episode's opening, which brought UCOS to the school to investigate. During this, Brian Lane was quick to point out Elizabeth's racist practices, as her school did not have any minority students, though Elizabeth responded by attempting to claim that the police force had a lack of minorities--a claim Brian debunked quickly. It was later in the episode that Eleanor Higgins, a former Peregrine student turned school secretary, confessed to killing Bowe after accusing him of cheating on her with her former friend, Melissa Parks. Eleanor claimed that she accidentally stabbed Bowe during her attempted suicide, and that she moved the body afterwards.
DSI Sandra Pullman did not believe that Eleanor moved Bowe's body herself, and other than Eleanor having an accomplice, it was revealed that Bowe was alive briefly before he was officially killed by the accomplice, who was revealed as Elizabeth. As it turned out, Elizabeth was present after Geoffrey Parks (Melissa's father) and Eleanor's mother were in a car accident years ago, with Mrs. Higgins being killed in the accident. Elizabeth took Geoffrey home right after, but she later blackmailed him into donating to Peregrine in exchange for her silence regarding Geoffrey's affair with Mrs. Higgins. Bowe had found out about the arrangement, as he was mumbling about it after Elizabeth arrived and helped Eleanor with Bowe's body. At that moment, the evil Elizabeth plunged the knife deeper into Bowe, killing him to maintain his silence.
Video of Eleanor and Elizabeth in the shed on the day of the murder, which was turned in by support worker Helen Hanley, revealed Elizabeth's role as a murderess and conspirator, though the villainess remained defiant during her interrogation. Elizabeth stated that Eleanor's emotional instability would prevent the claims from being believed, but Brian warned Elizabeth that Geoffrey would come clean and protect his business rather than the school, after which Elizabeth asked for a lawyer before her off-screen arrest.