European silver marks are quite fascinating. You can tell so much about where and when and by whom silver was made, and it's all in "code," like deciphering a note from a spy or something. If only glass were similarly coded!
Are the top and the bottom silver parts in the same pattern? I wondered whether they were perhaps applied at different times, and that's why there's a discrepancy in the town that Kev found. One set of marks is very nice and neat compared to the other, too. Not my area, it's just an idea.
The engraving is quite lovely. Thank you Jeremy for posting photos of it! Normally engraving isn't usually covered by silver if the engraver was aware it would go there, which supports the idea that the glass was made at a different time than the silver was applied.