From Neill Tools, Sheffield, this is the Eclipse No. 180 Instrument Vice, made around 1950. Now very rare.
It is a highly regarded tool designed for delicate precision work. With a swivel base and multi-angle capability, it is designed for holding small, delicate components for tasks like watchmaking or instrument making. It is iron and is known to be "indestructible".
Total length is 8", height is 4".
Note: The first three photos are from someone else, who had taken the time to thoroughly clean his. His photos show all of the features. The last two photos are mine; as you can see, it needs cleaning.
I can meet you with it anywhere on the North Shore, or I can mail it to you (with tracking).