Guest Stars Fiona Dolman as Sarah Barnaby Tamzin Malleson as Dr. Kate Wilding Natalie Mendoza as Sasha Fleetwood James Callis as Toby DeQuetteville James Callis as Julian DeQuetteville Kerry Fox as Betty DeQuetteville Paul Ritter as Harry Fleetwood Raquel Cassidy as Diana DeQuetteville William Gaunt as Ludo DeQuetteville James Clay as Simon DeQuetteville Louisa Clein as Amanda Harding Murray Melvin as Bentham DeQuetteville Eleanor Bron as Izzy DeQuetteville