These are named after the St. George’s chess club in London, where this style of play was used during club activities. Very popular until around 1850, when the Staunton sets replaced the prominence of the St. George’s sets. 

Most turners and manufacturers in the 19th century produced chessmen in this style, resulting in a variety of variation, materials, and qualities. St. George variations were also made in Germany and even in France (source: chess-museum.com).