Calvert Style Ivory Chess Set

An ivory set of the style attributed to John Calvert. This style of set was also made later by Lund and Merrifield, and probably others, and it appears in the Jaques pattern book, but those sets have Lund-type rooks, whereas these rooks and knights are typical of Calvert sets. Circa 1810-1820, if my dating is correct based on the features of this set.