Hi Trev!
I guess you already looked at Anders Steensen, Fredericia, Denmark? ref: Böje. See photo below. Not the exact font..but pretty close.
A wild guess from my side, (forum member Hose will certainly correct me if I am wrong) is that the base is later. The earliest hovedvandsaeg has no base (c 1730-1790), and the crude decoration and style of this one point in that direction, I think. The base is much more mid-late 1800s From 1800 and forward the heart shaped hovedvandsaegs was usually with a base. To confuse things even more the early hovedvandsaegs without base was usually hallmarked inside the lid..which this one aren't ..so perhaps I am completely wrong.
Another disclaimer: I have not looked at Norway yet ;)
Best,
Thomas