Jodie Whittaker as Mary Boon

Olivia Colman as Janet / Nurse Violetta Kiss

Emilia Fox as Kirstie

Daniel Mays as Charles Boon

Patrick Kennedy as Gerald Mills

Patrick Baladi as Dr Grant / Dr Steele

O-T Fagbenle as Jack

Nicholas Sidi as Nick

Marcia Warren as Elsie

Paul Nicholas as Alan Boon

Adam James as Mick

Angela Terence as Lizzie

Ben Addis as Frederick

Amy Marston as Margaret Boon

Antonia Kinlay as Lorelei

Robert Horwell as Brian