IMPRESSED UPPERCASE MARK AND DATE LETTERS MRH FOR 1879, REGISTRATION DIAMOND FOR 1875

See Marilyn Karmason with Joan Stacke, Majolica, New York, 2002, p. 70 for a page from Wedgwood's advertising catalogue, circa 1876, including this form; and The Harriman Judd Collection, Part II, Sotheby's, New York, 6 October 2001, lot 187 for a similar example.