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 Vinette Robinson as Sgt. Sally Donovan Yasmine Akram as Janine Danlevy Lara Pulver as Irene Adler Ed Birch as Tom Adam Greaves-Neal as Page Boy / Billy Ritu Arya as Gail Alistair Petrie as James Sholto Alfred Enoch as Bainbridge Alice Lowe as Tessa Debbie Chazen as Vicky Tim Chipping as Duty Sergeant Will Keen as Major Reed Jalaal Hartley as Photographer Nicholas Asbury as Landlord Wendy Wason as Robyn Oliver Lansley as David Helen Bradbury as Mum Georgina Rich as Charlotte