John — The two similar Webb registrations shown in Gulliver are 100456 of May 19, 1888 and 269928 of January 27, 1896. Neither are exactly the same. There seem to be several variations on this theme. I wouldn't have expected any one glassworks to have made several slightly different versions — this indicates to me that it's more likely that several glassworks were making them.
I wouldn't be surprised if 54494 (or possibly 154494) turns out to be class 4, earthenware, rather than class 3, glass.
As for engraved design registration numbers and lozenges, they're not particularly common. I usually have about half a dozen examples on my stand at the two big glass fairs, and I'm always happy to show them to anyone so long as I'm not otherwise busy.
Here's another example.
Bernard C.
