I have now discussed this with the the V. & A., and they have confirmed their agreement that this has its origins in the C19, somewhere. However, they didn't recognize the shape and were unable to help with it's exact use, although they agreed that a stand, or as a part of some more complex unit was a possibility. So, if anyone else has any bright ideas............

As usual my sincere thanks to the Glass department at the V. & A. for their time.