Guest Stars Rupert Graves as DI Lestrade Una Stubbs as Mrs. Hudson Louise Brealey as Molly Hooper Mark Gatiss as Mycroft Holmes Amanda Abbington as Mary Morstan Siân Brooke as Eurus Holmes Lindsay Duncan as Lady Alicia Smallwood Simon Kunz as Sir Edwin Tanya Moodie as Ella Paul Chequer as DI Dimmock Amanda Root as Emma Welsborough Sacha Dhawan as Ajay Charles Edwards as David Welsborough Eleanor Matsuura as DI Hopkins Gabrielle Glaister as Ambassador Marcia Warren as Vivian Norbury Daniel Hoffmann-Gill as Gold Teeth Man Aleksandar Mikic as Guard Harry Gostelow as Husband Eiry Thomas as Stewardess David Colbourn as Male Client Hattie Ladbury as Female Client Albert Magashi as Karim Rob Callender as Charles Welsborough Andrew Bone as Jack Sandeford James Holmes as Plane Passenger Edward Judge as Craig Neal Barry as Ray Kingsley Richard Syms as Vicar