Guest Stars Anthony Calf as Deputy Assistant Commissioner Robert Strickland Amy Nuttall as Caitlin Standing Storme Toolis as Holly Griffin David Newman as Robin Martin Turner as Hines Alun Raglan as Ethan Candida Benson as Ruth Taskerland Clare Cathcart as Harriet Danielle Carrington as Amy Taskerland Federay Holmes as Carla O'Brien Jack Shepherd as William Taskerland Lawrence Stubbings as Younger William Rosie Wyatt as Young Harriet Tom Ashley as Dominic