Hi,
this design doesn't appear in any of the catalogues that I can find, and isn't listed in Brian Slingsby's Guide to Whitefriars Paperweights. Having said that, it is shown in
Paperweights from Great Britain by John Simmonds where it is described as a P43A !!!
In that book the paperweight in question is "courtesy of Geoffrey Baxter". It could therefore have been a proposed design that never made it. However P43A is still a strange description as there is no information on a P42 or a P43.
My guess is that you have an example of a design proposal ( it is not the exact one featured in the book), and that indeed it was once refered to as a P43 in the initial stages of design.
I think it would be quite valuable to dedicated collectors.
Best wishes,
Tony