Guest Stars Idris Elba as Robert Gabriel James McAvoy as Gowan Ross Ron Donachie as John Ross Camilla Power as Joanna Sydeham Ronald Pickup as Sir Stuart Stinhurst Jonathan Firth as Rhys Davies Jones Gary Cross as Sergeant Lonan Naomi Frederick as Elizabeth Julian Wadham as David Sydeham Don Gallagher as Inspector Macaskin Yvonne O'Grady as Joy Barbara Horne as Solicitor Ravin J. Ganatra as Forensic Pathologist