This segment reunites Michael Powell and Leo Marks, respectively director and writer of the controversial 1960 film, "Peeping Tom". They hoped to interest the producer of this series, Herbert Brodkin, in setting up a spy movie which Marks had scripted and which Powell wanted to direct, entitled "Mr. Sebastian". Brodkin did eventually produce this movie (as "Sebastian" [1968]), but both Powell and Marks were replaced by others, which greatly annoyed them.
The Norman Foster who appears in this episode is not the American actor-director of that name, well-known for "Journey Into Fear" (1943) and other films, but the American-born opera singer who starred in Michael Powell's television film of the Bartok opera "Bluebeard's Castle". This appears to be his only non-singing acting role.