Thank you all - the quote from Page 72 kind of clarifies that perfectly.
Looking at p.64 the entry under Fast Talk explicitly says : "Fast Talk is specifially limitied to verbal trickery, deception and misdirection".
There is also that paragraph in the Investigators Handbook p. 101:
If the investigator is threatening violence or acting aggressively, the skill is Intimidate.
If the investigator is attempting to befriend or seduce, the skill is Charm.
If the investigator is using rational arguments and debate over a prolonged time, the skill is Persuade.
If the investigator is acting quickly to deceive, con, or trick, the skill is Fast Talk.
Thank you all for your help
Mister Wonderful