(Staffordshire Porcelain?) Zebra and Snake Spill Vases

This is a pair of (Staffordshire Porcelain?) that has been in my husband's family since his great great grandfather, who lived in England. I have a hand written note in the box tracing it back roughly 200 years by name, but no dates. The tradition on these was it was always passed to the oldest Bloxham son. My son would be the oldest 4 generations later. From what I can find online, none of them are marked (and prices are all over the board) These are original and do have grazing. It seems they could be anywhere from 1790-1840? Can anyone help me narrow that down? Is there a good place/way to date these? Also, how can I tell if it is truly porcelain because I did see some listed as enamelware, which I really doubt, they just seem to fragile.