The word 'hallmark' originates from the fifteenth century when London silversmiths were first required to take the items they made to Goldsmiths' Hall for assaying and marking. Only silver that met the required standard was marked - with the symbol of the leopard's head - a mark that remains the symbol of the London Assay Office today.
It isn't possible to detect an article's precious metal content by sight or touch, so a small piece of silver from the article has to be tested (assayed) to ensure that it meets the standard.
The techniques of assaying the quality of the silver and hallmarking have altered over the centuries, but the principle continues to provide buyers of silver items a guarantee of the quality of the silver. It is one of the oldest forms of consumer protection.
Precious metals are rarely used in their purest form but are usually alloyed with other metals. Sterling silver is 925 parts silver in a 1000 and this one of the marks you will see on an item of London made silver along with the leopard’s head. A Lion Passant also indicates that an item meets the quality of sterling silver.
The other hallmarks you will see are the mark of the maker, in our case ‘SH’ for Stewart Hersey, and finally a letter of the alphabet to signify the year the item was made. In 2015 the letter is 'q'.