This picture was planned as being the first of a series of spy movies featuring the character of Philip Calvert (in this film played by Anthony Hopkins). Around this time, it was known that Sean Connery would not be doing another James Bond film after Diamonds Are Forever (1971) and there was speculation that the Bond franchise might end. As such, a potential vacuum was sensed by rival producer Elliott Kastner. But when this movie failed at the box-office, plans for a film franchise to succeed the James Bond movies were scrapped.
The term "Eight bells" of the film and source novel's 'When Eight Bells Toll' title is a shipping reference to the hour of midnight. The phrase "Eight Bells" is also a nautical euphemism indicating "finished" as well as an expression stating the end of a sailor's watch (as in an obituary).
According to stuntman Bob Simmons's 1987 book 'Nobody Does It Better: My 25 Years of Stunts With James Bond and Other Stories', Simmons helped actor 'Anthony Hopkins' slim down and prepare for the lead role of Phillip Calvert in this film, a character who was a frogman, commando and Royal Naval officer.
This movie was made and released about five years after its source novel of the same name by Alistair MacLean was first published in 1966. 'When Eight Bells Toll' was MacLean's eleventh novel and this movie was the sixth film adaptation of one of MacLean's stories.
According to the film's production notes, producers Elliott Kastner and Jerry Gershwin commissioned novelist Alistair MacLean to write two more Philip Calvert spy adventure screenplays but when this film was not successful at the box-office, these projects went into turnaround.
Producer Elliott Kastner has said of this film: "Proportionately, it made more than Where Eagles Dare (1968), so I cannot say it disappointed me. But the distribution deals weren't as efficient as they could have been. I sold it to Rank for distribution in the UK, and that was all right. In the US, it went to one of the distribution companies owned by our financier, and that may not have been the wisest route in terms of market saturation".