de one troy pound of silver in weight, and the monetary value of 240 pennies also became known as a "pound". (240 actual pennies, however, weighed only 5400 troy grains, known as tower pound, a unit used only by mints. The tower pound was abolished in the 16th century.) The silver penny remained the primary unit of coinage for about 500 years.
Over the years, the penny was gradually debased until by the 16th century it contained about a third the silver content of a proper troy 24 grain pennyweight.
By 1915, a penny was worth around 1/6 what it had been worth during the Middle Ages. British government sources suggest that prices have risen over 61-fold since 1914, so a medieval sterling silver penny might have had purchasing power equivalent to £4.50 today, and a farthing (a quarter penny) would have the value of slightly more than today's pound (about £1.125).
From the time of Charlemagne until the 12th century, the silver currency of England was made from the highest purity silver available. Unfortunately there were drawbacks to minting currency of fine silver, notably the level of wear it suffered, and the ease with which coins could be "clipped", or trimmed, by those dealing in the currency.
In the 12th century a new standard for English coinage was established by Henry II — the Sterling Silver standard of 92.5% silver and 7.5% copper. This was a harder-wearing alloy, yet it was still a rather high grade of silver. It went some way towards discouraging the practice of "clipping", though this practice was further discouraged and largely eliminated with the introduction of the milled edge we see on coins today.
During the reign of Henry VIII, the silver content was gradually debased, reaching a low of 1/3 silver. However, in Edward VI's reign, silver purity was increased to sterling again and the first crowns and half crowns were produced dated 1551. From this point onwards till 1920, sterling was the rule.
By 1696, the currency had been seriously weakened by an increase in clipping during the Nine Years' War to the extent that it was decided to recall and replace all hammered silver coinage in circulation. The exercise came close to disaster due to fraud and mismanagement, but was saved by the personal intervention of Isaac Newton after his appointment as Warden of the Mint, a post which was intended to be a sinecure, but which he took seriously. Newton was subsequently given the post of Master of the Mint in 1699. Following the 1707 union between the Kingdom of England and the Kingdom of Scotland, Newton used his previous experience to direct the 1707–1710 Scottish recoinage, resulting in a common currency for the new Kingdom of Great Britain. After 15 September 1709 no further silver coins were ever struck in Scotland.
As a result of a report written by Newton on 21 September 1717 to the Lords Commissioners of His Majesty's Treasury the bimetallic relationship between gold coins and silver coins was changed by Royal proclamation on 22 December 1717, forbidding the exchange of gold guineas for more than 21 silver shillings. Due to differing valuations in other European countries this inadvertently resulted in a silver shortage as silver coins were used to pay for imports, while exports were paid for in gold, effectively moving Britain from the silver standard to its first gold standard, rather than the bimetallic standard implied by the proclamation.
The coinage reform of 1816 set up a weight/value ratio and physical sizes for silver coins.
In 1920, the silver content of all British coins was reduced from 92.5% to 50%, with a portion of the remainder consisting of manganese, which caused the coins to tarnish to a very dark colour after they had been in circulation for a significant period. Silver was eliminated altogether in 1947, except for Maundy coinage, which returned to the pre-1920 92.5% silver composition.
The 1816 weight/value ratio and size system survived the debasement of silver in 1920, and the adoption of token coins of cupro-nickel in 1947. It even persisted after decimalisation for those coins which ha