Guest Stars Fiona Dolman as Sarah Barnaby Tamzin Malleson as Dr. Kate Wilding Lia Williams as Maggie Markham Simon Kunz as Miles Rattigan Kobna Holdbrook-Smith as Rob Mead James Lance as Silas Raven Georgia Taylor as Bella Summersbee Una Stubbs as Audrey Braylesford Oona Kirsch as Suzie Colebrooke Ed Birch as Curtis Braylesford Liberty Mills as Cecilie Petersen Adam Kotz as Nick Summersbee Charlotte Cornwell as Jeannie Summersbee Howard Ward as Niall Colebrooke Timothy Watson as Vincent Treaborne Grant Russell as George Summersbee