I'm not a WF expert, but I'm sceptical of it being 9525 or 9526. If you look at the shape of the inside, yours is almost round, whereas the WF versions are triangular on the inside and outside - or to put it another way, in your piece, the glass gets much thicker at the corners, whereas the WF ones' walls are about equal in thickness all the way around. :?: :?: :?:
Needs Nic and Emmi (and David Fletcher if he's around...) to confirm or deny though.