Frank, that's interesting additional info. But have I understood it correctly? And what does "company not in 1946" actually mean?
Are you saying that Frank Eisner's move to Ireland was at the very beginning of the newly formed Waterford glassworks and that the location was Ballytruckle? From the wikipedia info on Waterford Crystal it states that the new company (after the closure of the original in 1851) was formed in 1947.
So is the new info you have given suggesting that Frank Esiner moved (presumably directly from Lemington) to Waterford (Ballytruckle) in 1947? And that in 1952 (or thereabouts) he moved back to England to be (or become) General Manager of William Swingewood's glassworks in Stourbridge?
As you suggested in an earlier post, I suppose the "M C" on the weight could conceivably tie in with the 1947 Waterford glassworks founders, Charles Bacik & Mirsolav Havel. Any guesses, though, on what the "W R" on the other weight, shown in the Scottish Paperweights book, could link to? [For general info, anyone checking the book will note that sadly no mention was made that the weight was engraved to the base with Waterford etc. - it was at that time included as probably made at Moncrieef's in the 1930s.]