Many references to Isaac Jamineu, third son of Claude, as the king’s consul in Naples.
Isaac wrote from Naples in 1754/55 about the erruption of mount Versuvius. See https://www.jstor.org/stable/104899?seq=1#metadata_info_tab_contents
Isaac is also mentioned in the book Patriot-improvers 1743-1768 by Whitfield Jenks Bell. For short biography see https://books.google.co.uk/books?id=dKBKSiIICH8C&pg=PA427&lpg=PA427&dq=Claude+Jamineau&source=bl&ots=tZeGZqSDp4&sig=Jr2A30FUCGnXUrL77LZ0oP-qlDA&hl=en&sa=X&ei=kbgrVdTDNM2PaKSQgMgH&ved=0CCsQ6AEwAg#v=onepage&q=Claude%20Jamineau&f=false
According to this account Isaac never married and when he died on 3rd November 1789 he left his entire estate to his niece. (Which one?)