u/Apprehensive_Ad4172

I was given this pencil which was bought at auction so I’ve got no idea about its origins. It might be silver and late 1800s. Or it might not! I’ve taken it to a specialist pen shop and they weren’t able to work out the best lead size- 2mm is too big, 1.5/1.6mm is too small. Any ideas what size lead and where to buy it? Given its age I’m guessing some weird Imperial measurement!