Here you have a couple of spoons which came my way. Attributed to John Stone of Exeter, 1855. What does worry me is a perfunctory representation of those 3 towers. They look to me more like some drum sticks or bones. Is that right?
I think if you were to clean the hallmarks (not that I would advise it) more of the design would become clear. In this period of the Exeter Assay Office, the dies for the hallmarks were being cut by the talented William Wyon and his son Leonard Charles Wyon: http://en.wikipedia.org/wiki/Leonard_Charles_Wyon