Jessica Raine Lucy Chambers Actor Peter Capaldi Gideon Shepherd Actor Kim Allan Young Sylvia Actor Benjamin Chivers Isaac Chambers Actor Meera Syal Actor Phil Dunster Mike Stevens Actor Talia Walker Bassols Meredith Warren Actor Rhiannon Harper-Rafferty Debbie Warren Actor Ramanique Ahluwalia PC Beth Courtney Actor Alex Ferns Nick Holness Actor Nikesh Patel Ravi Dhillon Actor Cecilia Blair Young Lucy Actor Johnny Allan Director Steven Moffat Producer Tom Moran Writer