Over 800 clay coin moulds, excavated from 85 London Wall in 1988, had been used for casting copies of silver denarii and copper-alloy dupondii and asses which dated from Trajan to Trebonianus Gallus. The discovery of the moulds in the ditch of Londinium's defensive wall led initially to thoughts that this was the concealment of incriminating evidence, but it is now recognised that counterfeiting coins was rife and perhaps even uncontrollable. The wide variety of moulds made it a complicated task to identify the numbers and types of coins used to make the moulds. This article describes the types of moulds found, examines how the moulds were produced, and discusses the prevalence of coin moulds at differing periods and on differing sites in Roman Britain and on the Continent.