Thank you very much for your reply and, above all, for the time you have taken to look into this for me. I really appreciate your help.

I am attaching the photograph of the J. & W. Pratt plate from which I originally found the complete “INDIANA / J & W PRATT” mark. As you can see, the pattern itself is very similar to mine, almost identical in its general design and decorative vocabulary, but not exactly the same.

I think I can therefore consider my research more or less concluded for the moment. Although I cannot make a firm attribution to a particular manufacturer, all the evidence I have gathered leaves me quite convinced that the pieces are mid-19th-century English refined earthenware, most likely Staffordshire.

The Pratt connection remains a very interesting possibility, particularly given your opinion that the backstamp itself is the same, but I agree that without an identical pattern or further documentary evidence it would be safer not to regard the attribution as definitive.

Thank you again for your kindness and expertise. Your comments have been extremely helpful in allowing me to understand these pieces much better.

Best wishes from Italy,

Marco