Does anyone know whether Darby's ‘Conversations on Romanism’ are real or fictional conversations in which he explains Catholic doctrine and his objections to it in order to convince his readers/listeners of biblical truth? AI suggests that Mr N., for example, refers to a certain Edward Nangle, a Protestant missionary to the Irish-speaking Catholic inhabitants of Achill Island, an island off the west coast of Ireland, who, although a contemporary of Darby, probably never met him.

They are fictional.  They were intended as a teaching format to get across deep subject in an manner that is accessible to every reader.  Whether Mr. Darby had any particular real person in mind is open to question, but I suspect he was simply dealing with the common questions and atticuted of his day.

At any rate, what matters is the truth conveyed.

Thank you, Mark.