Interesting point, especially as it seems to be on the small side for classic Bacchus. That said, our first classic Bacchus came from Canada; our second from Australia; our third from the USA - these items have a habit of moving around! And two of our Arculus door stops came from the USA too.
You may recall that John Hawley presented an analysis of 23 Gillinder paperweights in the 2006 Bulletin that split them into two clear categories: the beautiful facetted ones, with lead glass of SG around 2.81 to 2.89, and the unfacetted or less tidy ones made of glass of SG around 2.45 to 2.47 (ie soda lime glass). Mabel's weight, were it Gillinder, would fall into the second group. John Hawley and I between us have measured the SG of 21 'classic Bacchus' weights, and have found they all lie in the range 2.95 to 3.10. So an SG measurement on her weight should show clearly to which group it belongs.