Britannia silver, not to be confused with Britannia metal which is a pewter-like alloy which contains no silver, is a silver standard or silver alloy that was introduced in England in 1697 by Act of Parliament. This was to replace sterling silver as the only standard/alloy for “wrought plate” items. It contains 95.84% silver with the remaining 4.16% normally consisting of copper. Silver bullion coins such as British Silver Britannia coins, issued since 1998 by the Royal Mint, are minted in Britannia silver.
“The lion passant gardant hallmark denoting sterling was replaced with “the figure of a woman commonly called Britannia”, and the leopard’s head mark of the Worshipful Company of Goldsmiths replaced with a “lion’s head erased.” Britannia standard silver was introduced by the English government as part of the great recoinage scheme of William III from 1696, when attempts were made to limit the clipping and melting of sterling silver coinage. It was thought that by maintaining a higher standard for plate, there would be less incentive to put the newly issued sterling coins in the melting pot. Sterling silver was approved again for use by silversmiths from 1 June 1720, and thereafter Britannia silver has remained an optional standard for silver assay in the United Kingdom and Ireland. Since the hallmarking changes of 1 January 1999, Britannia silver has been denoted by the millesimal fineness hallmark 958, with the symbol of Britannia being applied optionally” (Wikipedia).