Thank you showing us this rare blue pearline piece, Margaret. I especially like the very delicate blue ground, and the opalescent detailing is particularly well executed in this example.
Davidson’ s unregistered pattern 134 sugar, cream and covered butter (most commonly seen in slag glass or opaque white or black glass) certainly have the 'shell & coral' motifs to the sides, but the unregistered pattern 166 sugar, cream and covered butter also have the same ‘shell and coral’ pattern though the pieces are, of course a different shape.
I know that it is commonly stated that Davidson bought most or all of the Heppell moulds, and I presume that, by implication from the marine theme of Heppell’s RD 390586 (24 November 1882) fish jugs and RD 374437 (6 December 188) shell design cream, sugar and covered butter, the ‘shell and coral’ Davidson 134 and 166 pieces were attributed as ex-Heppell moulds, but I am not aware of any contemporary hard evidence (documents or catalogues) showing the ‘shell and coral’ design as a Heppell design. Does anyone know of any such evidence, please? – in fact, are there any extant Heppell catalogues of any description?