Somehow the decoration reminds me of this Norwegian spoon featured here some time ago: viewtopic.php?f=47&t=53174
Maybe you or someone else could check the book mentioned in the thread. If it's Norwegian provincial silver it could explain the absence of assay marks.
Other explanation could be that it's British and the maker is duty dodger (usually the makers' mark is struck twice then). It looks a bit like one mark here: https://www.silvermakersmarks.co.uk/Mak ... ID.html#IB
[I B 1774 Candle snuffers Note similarity to the "possibly John Buckett" mark below] But based on the style Scandinavia would be my guess too.