Anthony Frieze provided one of the voices of Xoanon in the Doctor Who story The Face of Evil. He was a student at the school where Pennant Roberts' wife taught at the time. Philip Hinchcliffe arranged for a recording of his voice to be made shouting, "Who am I?", for the climax to part three. After the initial recording (in a sound studio), Frieze made a second visit to the set and re-recorded the line.