Benedict Cumberbatch Sherlock Holmes Actor Martin Freeman John Watson Actor Rupert Graves Detective Inspector Lestrade Actor Una Stubbs Mrs Hudson Actor Louise Brealey Molly Hooper Actor Vinette Robinson Sgt. Sally Donovan Guest Star Tanya Moodie Ella Actor Siobhan Hewlett Helen Actor Victoria Wicks Margaret Patterson Actor William Scott-Masson Sir Jeffrey Patterson Actor Sean Young Gary Actor James Duncan Jimmy Actor Katy Maw Beth Davenport Actor Jonathan Aris Anderson Guest Star Lisa McAllister Anthea Guest Star Philip Davis Jeff Hope Guest Star David Nellist Mike Stamford Guest Star Paul McGuigan Director Steven Moffat Writer Mark Gatiss Writer, Executive Producer Beryl Vertue Executive Producer