Sherlock Season 4: 20 Easter Eggs & References From The Six Thatchers

5. John's Therapist

Mary, of course, met her own appointment in Samarra in this episode. Shortly after her tragic death, we see a therapist talking about her loss to someone out of shot. It is soon revealed that this is Sherlock.

The scene works as a bait-and-switch as we have seen this therapist several times before on the show. It's Ella, as played by Tanya Moodie. She has previously appeared in both A Study in Pink and The Reichenbach Fall, treating John after a traumatic event in his life (his PTSD and Sherlock's 'death'). It's interesting that John has failed to go to her this time, but Sherlock has.