First of all I am impressed that you really did research some obscure sources to come up with your tentative attribution. I think it very reasonable to conclude that Thomas Hordley engraved this pattern. How the border design came to be on a sample plate ostensibly made for Davenport and on a production plate for Wedgwood may never be known, but I believe that there is a probable explanation. When Hordley's company produced a sample plate it seems he offered it to the client and they did not always choose to go with the border offered or indeed rejected the pattern completely. There is evidence within the group of Hordley plates that various borders might be developped before a final one was chosen- see Clews Zoological gardens and Ridgway Archipelago. In which case the rejected border could be tried with a different design and offered to the same or a different client. As we have not yet seen a Davenport production plate with this border it maybe never went into production for that firm and became available for Hordley to offer elsewhere. And we know from other playes in the group that Hordley did supply patterns to Wedgwood So in conclusion -I think it perfectly reasonable to conclude that your Hollyhock plate was engraved by Hordley for the Wedgwood company. Whae a great find!