NOTE: Sid Lethbridge - The Dog with Rabbit in Mouth Etching is found on goblets and blown light tumblers. There is a similar etching where the dog is facing to the left.
For the purposes of my research the firm that did this etching has designated as U1 i.e. Unknown 1. They were very prolific and there are about 30 etchings that can be assigned to them.
Ref. Etched Pattern Glass, Acid Etched Goblets and Tableware of the 1880s, p 119