Hi Chris,
I was not ignoring this, feeling I could contribute nothing useful, but you bumped it.
This appears as "possibly SU or a Scandinavian factory" in Judith Miller's Collectables Price Guide 2007, for a reason.
I am not prepared to state that this is SU, when I have seen no documentary evidence to suggest that it is. This, and another vase which regularly appears on eBay with a pronounced foot and triangular patterning in a similar style to your vase, have defied a positive attribution, and the vase with triangles has been attributed by others, to SU and Ruda, amongst possible candidates.
regards,
Marcus