Last appearance of Mr. Jocelyn played by the late Timothy Bateson who died on the 15th September 2009 (age 83)
The producers clearly wanted to suggest a botanical name with title of this episode, 'Orchis fatalis'; orchids get their name from a resemblance to the testicle. So, the title could be translated as 'Fatal testicle'.
Captain Tucker wears the regimental tie of the Brigade of Guards; Munro Hilliard wears the club tie of the Marylebone Cricket Club.
Harriet Walter plays Margaret Winstanley in this episode. She returns in episode 15.4, Death and the Divas (2013), in the role of Diana Davenport.
Marty Cruikshank plays Madeline Villiers in this episode. She returns in episode 19.2, Crime and Punishment (2017), in the role of Cecily Hope.