The first person named BLATCHFORD in Gloucester Mass (actually: he lived in the town of Sandy Bay>Gloucester>Rockport)was John BLATCHFORD, b.abt 1702 in southern England (Devonshire?).He married 2 Jan 1755, Rachel CLARK(E) in Sandy Bay.They had several children there.
Their son, John BLATCHFORD; served as a cabin boy aboard the HANCOCK before it was captured by the British in the Rev War.His experiences as a prisoner and his subsequent escapes were told in a wonderful book: the Narrative of John Blatchford, which has been reprinted over the years.It is very interesting reading.
You are most likely descended from the first John, and maybe from the second, as I am!The Essex County Genealogical Society (or whatever their name is) has access to a copy of the aforementioned book in one of the county libraries.They are located in Lynnfield, MA at the town library, as I recall. Anyhow, lots of luck, cousin!