The film was made and released about two years after its source novel of the same name by author Len Deighton had been first published in 1974.
The only spy movie theatrical feature film adapted from a Len Deighton story made during the 1970s decade.
This was the second spy film for Derren Nesbitt, four years after having made "Innocent Bystanders."
Although this Len Deighton adaptation does not feature the nameless character known in films as "Harry Palmer" (and played in them by Michael Caine), it does feature two regular characters from the Harry Palmer series of books, his boss Dawlish (who does not appear in the films) and the Russian spymaster Colonel Stok, who had been played by Oscar Homolka in both "Funeral In Berlin" and "Billion Dollar Brain".
First filmed adaptation of a Len Deighton spy novel since "Billion Dollar Brain (1967)" around nine years earlier.