See Geoffrey A. Godden, Coalport and Coalbrookdale Porcelains, New York, 1970, p. 122, fig. 204 for a similarly painted pair and fig. 233 for a line drawing of a similar vase illustrated by Jewitt and exhibited in the International Exhibition of 1871. Also see Michael Messenger, Coalport 1795-1926, Woodbridge, England, 1995, p. 35, pl. 31 for a similar pink-ground vase executed by Randall with variantly gilded key-pattern foot. Though noted here as 'The Exhibition Vase', the present example replicates the drawn image more precisely. Please also note that Coalport artists 'were not allowed to sign their work until later in the century, however Randall bird's became famous in their day as had William Billingsley's roses a generation before.' See Geoffrey A. Godden, Victorian Porcelain, New York, 1961, p. 38-39, fig. 10.