I'm working on an extensive write-up on the manufacturer of the early 'Magnum Bonum' razors and I should have it done later today.

The short version is: they were made by a Marsden.

The detailed short version is: they were probably made by George Marsden. Or Benjamin. Or maybe Robert. Would you believe Richard Marsden?

(There were 54 Marsden children apprenticed into the cutlery trade in Sheffield from 1732 to 1810, and all the razors are just stamped 'Marsden').