Auction Find - Unusual Hallmarked British Silver Antique Pocket Watch

I will start by saying I don't have a clue how much this one is worth! My husband found it in a bag of cheap costume jewelry. The casing is solid silver and rather frustratingly I have been unable to read the hallmarks. We also don't know who the maker is, but it does have a serial number. The watch is missing the glass, hands, and winding key. There is also damage to the hinges. We were unable to open the back to check the movement as there are 4 tiny screws securing the back cover that would need specialist removal. I listed it for R750 ($58) and will just have to see how it goes!!! 

This watch weighs 110g and has a 5cm diameter. I simply love the snake detail around the hinges.

Thank you for reading! @onetree