Guest Stars El Anthony as Mark De Costa Anya Cooke as Young Napper's Sister Deka Walmsley as DCI Mick Wickerson Charlie Carter as DC Martin Long Jonah Collier as Young Robert Napper Katie Buchholz as Rachel Nickell Tom Colley as Young Napper's Father Maria Louis as Young Napper's Mother William Owen as Journalist Stuart Cooke as Mr Wood Stewart Allen-Smith as Policeman at Door