One year on, and I find a companion for my decanter...
A broad goblet with wrythen trumpet-shaped foot. Very similar mould, and an identical colour, so I believe them to be from the same factory.
Does the style shed any light on its manufacture? It looks quite Germanic to me, but then the Scandi countries, assuming it is c.1880-1900, were heavily influenced by glass from Germany and Bohemia at this time.