SOLVED - DITCHFIELD PLAQUE
Hi to anyone who tried to help me on this!
I eventually hit upon the idea of approaching Glasform (John Ditchfield's company) direct, and received a reply from Karen Ditchfield to say that the head wall plaque was definitely made by them.
Apparently very few of the paperweights had the drilled-out hole to hang, and she knew of one other that had been in the stock room, and imagined mine had been sold from there. However, as they were never sold online, and she could not remember ever having sold one, she told me that not many were made and so it's rare.
This is good news for me as I only paid £10 for it.
Thanks anyway to those who looked - I thought you'd like to know and the topic can be closed.
Best wishes
Sheila.