This might be another Czechoslovakian product in origin, but could be wrong, and today spent a fruitless hour at the National Archives looking for the Regd. No. without success.
The smooth mirrored base carries an acid backstamp which reads..........STELITE - FOREIGN........and across the centre is Regd. No. 331352, which not in the British Blue Book, (a fabric Registration in the Archives) - also tried 331852, which another fabric Registration.
In the British sequence of Registrations these Nos. would date to 1898/99, and a tumbler with acid stamp such as this is almost too early to be from that period anyway. I believe there are series of Continental Rds., so this one may well be from a non U.K. list.
I've tried variations on the word STELITE on the Board's search with success.
Height is just over 4" (105mm)
Very similar to the basic shape of Crystolac and Durit tumblers - height is just over 4" (105mm), and has an acid motif which reads Trinity College Cambridge - so very prestigeous association
Looking for assistance please, and grateful if anyone has ideas. thanks for looking.