I think it is a standard Murano, on the basis of the "very coggy" canes used, such as with many Fratelli Toso, Ferro & Lazzarino, etc. items.
Referring back to a thread from six years ago:
Only 50 Royal Brierley Paperweights all over the world???, I do not know whether Bob Hall's information in his book, told to him by folk at Royal Brierley, was accurate but the book info states "four designs" and that the base (ground?) was either blue or green.
So, if the detail in the book is correct, then a clear ground does not fit for the Royal Brierley millefiori weights.
Also, in that other thread Alan Thornton referred to his website page for his "Murano Project".
The weight being referenced is this one. And the overall look of the canes and the general features of the weight are very similar to the example shown in Bob Hall's book. They do not have the "very coggy" canes.
However, it would useful to know whether anyone can show examples of other Royal Brierley labelled (or otherwise marked) millefiori weights that can prove the existence of "more than 50" or any with a clear ground.