Calvert Chessmen History- By Frank Camaratta Jr.:
This style English Pattern playing sets was manufactured in the U.K. starting around 1820 and is attributed to John Calvert, a Master of the Worshipful Company of Turners, located at 189 Fleet Street. His company specialized in exquisitely turned Chess sets in ivory for the more wealthy English subjects and in Boxwood and Ebony for use in the coffee shops and clubs where Chess was a popular pursuit.
Chessmen of this type were actually manufactured throughout the early-to-mid 1800s. John Calvert was one of the leading chess set makers in the U.K. from 1791 until his death in 1822. The Calvert Business was then run by his widow, Dorothy, until her death in 1840. Many sets of this design can be found at antique auctions in the U.K. that were not produced in the Calvert workshops, but were likely copies produced by other makers of the period. Apparently, copyrights had little meaning back then, as now.
The Calvert pattern was ultimately eclipsed by the Saint George Pattern, which was a modification of the amorphous English pattern sets popular from the late 18th century to the first half of the 19th century.
The Calvert playing sets had virtually disappeared by the time the Staunton pattern chessmen were introduced to the public in the fall of 1849 by the firm of John Jaques of London.