Main •
Margaret Lockwood as Harriet Peterson •
John Stone as Doctor Ian Moody •
John Bryans as Arthur Bollington (season 1, episode 2) / William Corletti, Senior Clerk at Harriet's Cahmber. (seasons 2–3, 22 episodes) •
Philip Stone as Sir John Gallagher
QC, head of Harriet's Chamber. He later becomes a judge. (seasons 1–2, 11 episodes) •
Anthony Valentine as Robert Miller (season 1, episode 11) / James Eliot (season 3, 8 episodes) • Rosie Collins as Rosie (season 3, 8 episodes)
Guests (partial) •
Alun Armstrong as Bob Graham (1 episode) •
Angela Thorne as Eileen Rutherford, a social worker (3 episodes) •
Brian Wilde as Latimer / Prison Doctor (2 episodes) •
David Graham as Farber Tapworth (2 episodes) •
Ed Devereaux as Frank Ronce (2 episodes) •
Geoffrey Whitehead as Brian Bex / Major Bilton (2 episodes) •
Gerald Cross as Judge (2 episodes) •
Joss Ackland as Sir Robert Beste (1 episode) •
Leon Vitali as Brian Parsons (2 episodes) •
Michael Coles as Detective Sergeant Gable (3 episodes) •
Paul Eddington as Cooper / Kendall Blumenthal (2 episodes) •
Percy Herbert as Supt. Kellaway (3 episodes) •
Peter Blythe as Sommerfield (2 episodes) •
Peter Sallis as Coroner (season 1, episode 8) •
Raymond Huntley as High Court Judge (2 episodes) •
Sarah Douglas as Jenny Deane (2 episodes) •
Veronica Lang as Secretary (season 1, episode 11) ==Plot==