Please can you help me identify the maker's mark on this pocket watch? I'm told it was my great (maybe a couple of times) grandfather's. I'm completely new to identifying the silver marks, and have worked out so far it was made in London in 1883? Part of the maker's mark is missing so I'm thinking either LO, IO or JO?
The key mentions a watchmakers from Walsall, "Sheppard Bros"? But if the Walsall I'm thinking (and where my family are from), that's in the midlands, not London! Could the key have been added afterwards?
Apologies for its slightly grubby state - it needs a good clean!
More pictures here: https://www.flickr.com/gp/145751259@N06/V3okWa