ther’s a manual by Hooper and Phillips that shows a trident mark belonging to Caughley co in SHropshire in the 1700s but this piece seems more modern. thanks
same pics are here:
Are you looking at asking prices or sold prices !! Post the link that you found to those prices !! Anything with a crack unless historically important is less than half the retail value and that is for high end items !! For dinnerware or more ordinary items its just whatever you can get !!
https://www.ebay.com/sch/i.html?_from=R40&_nkw=Swansea+pottery&_sacat=0&rt=nc&LH_Sold=1&LH_Complete=1
Here are the recent sold items from Ebay !! This is what people are actually paying for this pottery !!
some real nice stuff here:
http://www.worldcollectorsnet.com/articles/swansea-nantgarw-pottery-porcelain/
look at the prices for plates here:
https://anthemionauction.com/journal/nantgarw-and-swansea-porcelain/
these are the high end hand painted plates; the stuff in that link you sent is mostly transferware. Some of the handpainted stuff that you linked did get over a 100 but how knows if the people were just getting rid of it; or they didnt know what they had or it’s not that great. I dont know.
the plates in this link would be about $600 before the british pound went south after brexit etc.