Is the pontil mark broken, or does it have a blob of glass stuck on it with an indent in the middle of that?
From the pic there, it
almost looks like an IoWSG coachbolt mark. But the vase itself looks similar to ranges much, much later than coachbolt marks.
So I can't suggest IoWSG, really, but I do wonder a little bit about their "Glassmaker's Shelf" stuff.
Things made by the makers for themselves, encouraging them to learn and use their own takes on designs, and the work sold in the shop, from this special "Glassmaker's Shelf".
I might be barking up a tulip rather than just the wrong tree.
