I too have one of these Lassman combination padlocks, and did a little research on it for my book “Unlocking the Portals of History.”
Lassman is not strictly a lock or hardware manufacturer. The firm was founded by Samuel Lassman on December 31, 1941. Mr. Lassman produced a number of items he designed or invented including corkscrews and bottle openers. In 1986, the company was purchased by Lawrence Churchill Ltd., “Manufacturers of Quality Die Cast Products.” They still produce the padlock.
According to a letter I have from the late Jim Evans, Lassman locks were purchased by J. Banks of Excelsior Works for resale along side their own manufacture.
Hope this information helps. Can you give us the U.K. patents?