Mike Pim-Keirle sent this item to us as a query. It is a tool which frequently turns up at car boot sales and the like and I thought it worth putting on the website and providing some background, courtesy of Jane Rees.
This is an engineers’ adjustable screw plate used for forming the thread on wire. It would have needed a die to accompany it to make the correct sized screwed hole.
Attached is an image from a Ward and Payne 1911 catalogue illustrating such a tool.