The village with the pub is in Aldbury Hertfordshire, the pub is called the greyhound and has been used in many films including the Dirty Dozen
The opening titles are narrated by an uncredited voice. This is actually actor David Bauer who has a guest star role in the fourth episode "The Experiment".
This was Madalena Nicol's final screen role. Returning to her home country Brazil in the early 1970s, she resumed her work in the theatre. In the late 1970s, she taught drama at the Houston Academy of Dramatic Art in Texas.
Village where Craig & Richard go to the pub is same as Avengers episode Murdersville.