Guest Stars Nina Wadia as Dr Anita Rhys Evans Jamie Sives as Karl Mortensen Karl Johnson as James de Cadenet Chizzy Akudolu as Addy Smith "The Squeak" Eileen Davies as Julia de Cadenet Risteard Cooper as Si Robertson Isabelle Mullally as Annie Thea Barrett as Polly Henry Helm as Josh Grace Calder as Savannah Islah Abdur-Rahman as Nav Jackie Clune as Leah Worthington Paul Chahidi as Phil Cook Barbara Drennan as Hattie Alex Hughes as Adrian Joan Iyiola as Anya Adetola Rina Fatania as Headmistress James Doherty as Blair