Guest Stars Fiona Dolman as Sarah Barnaby Tamzin Malleson as Dr. Kate Wilding Hannah Arterton as Katy Jamie Blackley as Duncan Hendred Joanna David as Mother Julian Rosalind Knight as Mother Jerome Martha Mackintosh as Tamsin Bickford Louise Bangay as Serena Fleming Cliff Parisi as Barry Susan Sheridan as Mother Thomas Fiona Glascott as Sister Catherine George Irving as Matthew Hendred Emma Davies as Lauren Hendred Jessica Turner as Delia Norrington Philip Anthony as Peter De Winter Zoë Lister as Young Mother Julian Tom Knight as Colin Fleming Michael Colgan as Father Behan Richard Walsh as George Norrington Josh Parris as Callum Hugh Ross as Bishop Graves