Well, oohshiny, our lack of a response is actually a collective “duhhhhhhh” - we just don’t know. I’ve looked in all my refereence books for the “C&S” and don’t see anything, but the mark that throws me the most, and probably some of the other people, is the one word “silver”…its just not a word we see on silver without some other word such as “sterling”, “coin”, “plate”, “nickel” or the like. Very unusual.
Sorry, but you can be sure a lot of very experienced folks have looked at it. And just for the record, those are the only marks?