My greatgrandmother was Elizabeth Gellizeau, married Banfield in St.Vincent. Information about her is sketchy. She died before my 84 year old mother was born, hence the lack of information. I am presently investigating. She lived around the time you mentioned that your grandfather lived.
My mother tells me about the Sardine family, who owned a bakery in Kingstown and thinks there is some relation.
Wish I could write to you directly.