Tortoise shell with silver stamps - help required

Hello! Recently, I found a sizeable collection of antique tortoiseshell artefacts in a goodwill store. They were initially purchased for their purely decorative appeal, but later I discovered they were all genuine tortoise. Amongst them, I discovered a belt or cloak clip with sterling silver clasp. It is hallmarked, but I am unable to determine exactly what it is Im looking at as I have very little knowledge of silver marks. I am hoping to date it, and/or learn it's origin.
Can anyone assist?
I would like to gather more info on the other pieces, but Im not sure which forum to post tortoise products in (this is the only piece with silver). In the jewellery forum, perhaps?
Thanks in advance for any help offered.

 

British 19th C sterling mark, missing the town and lion. There may be on the other part. Or just missing. I'd be sure it was as marked.

 

Thank you. Alas, there are no other marks. The other part is a brass(?) bar that it clips to. You can see it in picture 2.

 

If they are jewellery you can, otherwise Antique Discussion is fine.