Tremayne

 was the headmistress of Tremayne Academy. She was heavily religious. She complained to Lt Peter Sandoz about the missing students. She was insistent that the devil was trying to seduce her.

Tremayne tried to kill the Fifth Doctor, Peril Bellamy, Alison Speer and Nyssa in the name of purification. She was shot by Sandoz. (AUDIO: Winter for the Adept)