Of course I could be wrong but looking at the bottoms I would still cast a vote for mid century and later in date. Correct me if I am wrong you are holding a bowl up in the last picture, in the first set it appears that the saucers are low rimmed. Anyway I am not sure how the dealer you purchased them from came up with the date of 1870's without marks this could be a hard one. Which In general there was much pride in those days of manufacting and esp. in the staffordshire area, and most likely would of been marked, Unmarked usually says newer, cause they used Foil or paper labels, and sometimes neither if they were boxed together in a set, and the box was marked with the maker and country, all this would point to Mid century and later, but again without a mark to go on we would have to search 1000's of images top try and find the pattern and maker and then we could get a date.