Frederick Forsyth's 1971 novel "[The Day of the Jackal](https://en.m.wikipedia.org/wiki/The_Day_of_the_Jackal)" remains an immortal political thriller that defined the 'assassination novel' in popular consciousness. What has always intrigued me is the small but significant Charles Calthrop plot-element. This was a person in the novel whose name was used by the Jackal as  one of his identities. Wikipedia notes that

>Charles Calthrop is the name of a former small-arms salesman who was in the Dominican Republic at the time Rafael Leónidas Trujillo was shot. The SIS later heard a rumour that Calthrop has helped the partisans kill Trujillo by shooting the driver of his armoured car, causing it to crash. In the book, the British police originally think Calthrop is the Jackal's real name, until the real Calthrop shows up at the end, after the Jackal's assassination attempt was thwarted. The authorities were misled by the fact that chacal (i.e., Cha[rles] Cal[throp]) is French for "jackal". 

Source: https://en.m.wikipedia.org/wiki/Jackal_(The_Day_of_the_Jackal)

If I remember right, the name of Calthrop cropped up in a routine enquiry about possible aliases the Jackal might be using, but the police became excited about its possibilities when the person was found missing and his name parts seemed to spell out "cha-cal" which is French for "jackal". Although revealed a coincidence at the very end, this detail energized the search for the Jackal and helped authorities put him under pressure.

How critical was the Charles Calthrop element in foiling the assassination?  Did the wild coincidence mean pure bad luck for the Jackal, or was the investigators'   policy of following up every possible lead (especially persons who were untraceable during that crucial time window) simply an example of good and meticulous detection?

[Please include adequate references to support your answer, so as to avoid any objection of being "primarily opinion based."]