Rod Steiger turned down the lead in this episode.
This show was repeated April 26, 1967.
This was available on home video in the U.K. in the early 90's on a tape called "TV Heaven-1966" (#VO658) but is no longer in print.
The LeCarre short story first appeared in the Janurary 28, 1967 issue of The Saturday Evening Post.
This episode included scenes filmed on location near the East German border.