Hi Bryn,
Yes, the seller is quite correct. This is by Stennett-Willson, from the same textured range as in the other thread by Pip. It is from the textured range pattern number RSW 26 - Kings Lynn and Wedgwood.
You have to be a bit careful using the term
Rustic with RS-W, since it applies to one of the ranges that he designed - but I fully understand your use to describe the vase
Hope that helps, Nigel