Medieval pewter sometimes has scratched symbols on the underside which are believed to be merchants' marks. Medieval pewter is, however, fairly rare.
With the advent of mass manufacture of household pewter wares in the 18th and 19th centuries, makers especially in Birmingham, London and Sheffield, often sold large quantities of marked or, more usually, un-marked flatware and hollow-ware to wholesalers and retailers in the major cities. Many of these sellers then stamped the items with their own marks, thereby creating later confusion for collectors!