Hi new to the forum, can anyone help identifying these hallmarks, any help much appreciated
This is a British electroplate mark, not a silver hallmark. The clues are in the EP (for electroplate) mark and the A1, which shows that the plating is the maker’s best quality / thickness. D&S are the manufacturer’s initials but I don’t know for sure who they are. The 6 figure number beginning with Rd is the design registration number. 120841 was issued during 1889 so we know that your butter server was not made before that date but it could have been made any time after that.
Thanks very much Phil