Guest Stars Nina Wadia as Dr Anita Rhys Evans Karl Johnson as James de Cadenet Jamie Sives as Karl Mortensen 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 Jackie Clune as Leah Worthington Islah Abdur-Rahman as Nav 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