Mary, Thank you for your post – I had forgotten about the book by Simon Green and it partly answered my query. I will order the papers of Horace Jones from family search in the hope that it mentions the christian name of the Miss Farmer who married Jeremiah Pratt. According to the will of John Farmer he had at least three daughters Mary, Anne and the daughter who married Jeremiah Pratt.
The Simon Green book mentioned an Elizabeth (daughter of Robert Pratt and Anne) who married an Andrew Kelly in 1720. I suspect that this Andrew Kelly (a mariner) was the son of another Andrew Kelly (also a mariner) who married Anne Farmer, daughter of Captain Thomas Farmer on 10 Aug 1675. Geoff