Thank you all for your suggestions. It is a real puzzle, this one.
I agree that the canes in the base and those in the bowl look as if they could be from different sources, and it certainly feels modern to me. That said, as I have been working through some of my many images of paperweights, I am increasingly drawn to a Perthshire attribution - possibly for the base canes too. The canes in some PP1/PP2/PP3 weights are quite like those in the bowl, and some of the mid 1980s weights have complex canes of a similar style to the base ones.
Andy - I thought that Caithness made the Edinburgh Crystal weights to begin with, before the contract went to Murano? So there may be no such thing as Edinburgh Crystal canes...but perhaps one of the Scottish glass experts could confirm or correct this?