Topic: Huge,I mean huge and heavy banjo shaped black/smoke vase/bottle/jar. ID please?

[jeanne]

Yet another donation to the Isle of Wight Hospice. This enormous lump of glass is very handsome. I stands 33cms/13ins tall, is 27cms/ 10.5 ins wide and is 14cms/5.5ins front to back. The neck which is the darkest, just about black, is around 1cm thick. The base shows signs of wear, has the remains of some kind of label and a ground pontil. The flat sides are not completely flat, caving in slightly at the top and bulging slightly at the bottom.
Ideas of value, whatever it is, would be useful for selling in the shop.