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 Tanya Moodie as Ella Simon Kunz as Sir Edwin Lindsay Duncan as Lady Alicia Smallwood Paul Chequer as DI Dimmock Charles Edwards as David Welsborough Amanda Root as Emma Welsborough Marcia Warren as Vivian Norbury Sacha Dhawan as Ajay Eleanor Matsuura as DI Hopkins Aleksandar Mikic as Guard Daniel Hoffmann-Gill as Gold Teeth Man Gabrielle Glaister as Ambassador Rob Callender as Charles Welsborough Eiry Thomas as Stewardess Hattie Ladbury as Female Client Harry Gostelow as Husband Neal Barry as Ray Kingsley Richard Syms as Vicar Edward Judge as Craig James Holmes as Plane Passenger Andrew Bone as Jack Sandeford Albert Magashi as Karim David Colbourn as Male Client