[1] Duncan is said to have been versed in mathematics and theology, as well as in philosophy, and to have acquired such a reputation for medical skill that James I offered him the post of physician in ordinary at the English court, and even forwarded to him the necessary patent; but to have declined the royal invitation out of regard to his wife (a French lady), who was reluctant to leave her native land.
He is said to have been shielded from the vengeance of the clergy only by the influence of the wife of the Maréchal Urbain de Maillé-Brézé, then governor of Saumur.
[1] Duncan also wrote a treatise entitled Aglossostomographie on a boy who continued to speak after he had lost his tongue, pronouncing only the letter "r" with difficulty.
The faulty Greek of the title, which should have been Aglossostomatographie, was very severely criticised in prose and verse by a rival physician of Saumur, named Benoit.
After the Revocation of the Edict of Nantes in 1685, Mark and Suzanne's granddaughter Suzanne Martin, daughter of their daughter Rachel, differed in opinion so strongly from her husband Moïse Poitevin, of another large Saumur Protestant family, that they separated: he abjured and stayed in France, but she left c. mid-1688, first to England, where she did her "reconnaissance" at Leicester Fields Huguenot Church, then to Rotterdam where she bore her last-born, Paul Poitevin, in December 1688, whose godfather was Pierre de Monnery, father-in-law of minister and pastor Daniel de Superville.