Antique Silver Rimmed Horn Cup

I purchased this Silver Rimmed Horn Cup on Ebay 20 years ago. It has been displayed ever since I received it. It is very thin and very delicate horn and from the base mark it looks like it has been turned and shaped from the outside. I do believe it is very old as the silver hallmark looks like 1864 but as it has worn from use I could be wrong. I have since found that the maker is Peter & Ann Bateman 1791-1799 London. The assay make in picture 4 is P B over A B. a queens head, a lion and a letter B.
Hope everyone enjoys these pictures and if you require any more just ask.