thanks and yes, zooming in does make for a much clearer image. It's usually pressed glass that is Registered, not cut glass, although some pressed Registered designs have additional decoration in the way of real cutting. Zooming in makes it appear more like cut glass, at least to me.
Suppose we could always ask the Birmingham Museum to check for us, assuming they know. They don't provide any provenance as to the claimed attribution - presumably from some catalogue or advertisement perhaps.
It would have been made in two parts originally anyway, whether pressed or cut, and then joined.