Guest Stars Emily Mortimer as The Bolter Will Keen as Sir Leicester Beattie Edmondson as Louisa Radlett Abbiegail Mills as Moira (Aged 6-12) Zino Masoud as David (Aged 6-9) Kitty Archer as Lavender Davis Heather Rome as Lady Kroesig Joanna David as Elegant Paris Society Woman #1 Alex Kelly as Baby Moira's Nurse Mabli Jên Eustace as Pixie Martha West as Jassy Radlett Henry Rylands as Randolphe Pine Penny Mortimer as Elegant Paris Society Woman #2 Emma Cater as Boring Don's Wife Alexandru Batareanu as Boris (Bookshop) Godeliv Van den Brandt as Revolutionary Catalan Woman Dominic Geraghty as Important Person at Kroesig's Sam Nivola as Matt Paul Lacoux as Gare du Nord Ticket Seller Chooye Bay as Bookshop Comrade