Charlotte Ritchie Alison Actor Kiell Smith-Bynoe Mike Actor Jim Howick Pat , Plague Victim Actor, Writer, Executive Producer Martha Howe-Douglas Lady Button , Plague Victim Actor, Executive Producer Mathew Baynton Thomas Thorne , Plague Victim Actor, Writer, Executive Producer Simon Farnaby Julian , Plague Victim Actor, Executive Producer Lolly Adefope Kitty , Plague Victim Actor Ben Willbond The Captain , Plague Victim Actor, Executive Producer Laurence Rickard Robin the Caveman , Plague Victim Actor, Executive Producer Katy Wix Mary , Plague Victim Actor Yani Aleksandrov Headless Humphrey's Body Actor Rosie Cavaliero Fiona Legge Actor Tom Kingsley Director Matthew Mulot Producer Alison Carpenter Executive Producer Debra Hayward Executive Producer Alison Owen Executive Producer