Again, I believe I have at least partially answered my own question. I found an identical piece at:
(admin edit - see Posting Requirements )I can find no reference to "S.G Silverplate" on any silver reference site. Since the font of "S.G" is similar to that in the Silver Guild shield logo, I am thinking that it may have been made by the Guild for export to be marketed by others. The plain tipped handle design is similar is Guild pieces I've seen on sale.