Modern decimal currencies are easy enough for moving decimal points, but like the metric system, they lack depth and practicality. For centuries, the British pound-shilling-penny system provided a framework that divided naturally, supported trade, and carried cultural meaning. Its complexity was not a defect but a strength.

The Atrocity of Decimalization

Although decimal coinage may seem intuitive to us now (100 cents to a dollar or Euro, 100 pence to a pound, 100 kopeks to a ruble, 100 fen to a yuan, 100 centavos to a peso), it did not arise naturally but was a byproduct of the French Revolution, which also gave us the infernal metric system.

As with the metric system of measurement, there is no natural convenience to subdividing a unit of currency into 100 parts beyond the ease of multiplying or dividing amounts by factors of 10, something that is rarely - if ever - done in real life.

The French system

Since France inflicted the decimal system upon the world, let’s take a brief look at their system of coinage.

Prior to decimalization, the Ancien Régime currency system of France served merchants and customers well for over a thousand years, from 781 to 1794. Its basic units were the denier, sou, and livre:

Livre is the French word for pound (libra in Latin) and was originally equivalent to the value of one pound of silver. Its symbol is ₶. Similarly, a British pound sterling was the value of a tower pound of silver. The tower pound was a medieval unit of weight equivalent to 5,400 Troy grains, and was replaced by the Troy pound in 1527.

As we’ll see, a sous is analogous to a British shilling and a denier is analagous to a British penny:

240 deniers = 20 sous (or sols) = 1 livre (₶)
240 pennies = 20 shillings = 1 pound (£)

An écu was a larger silver coin, originally gold, that was worth 6 livres or 120 sous.

Coins under the French system included the following, although some denominations changed over time:

What about the franc? While the franc later became the primary unit of account in France, it was created in 1360 as the first coin worth one livre tournois, and was minted as a gold coin to pay the ransom for King Jean II during the Hundred Years War. It transitioned to silver between 1577 and 1641.

One challenge with much of the coinage of the Ancien Régime is that coins did not have a fixed value. Their value was related to the weight of the metal they contained. These values changed over time. The écu was originally a gold coin and later minted in silver. Deniers were silver coins but later transitioned to copper, along with the liard.

While this system worked well, the variety of denominations over time as well as their changing values create a bit of complexity. We will focus on the British pound-shilling-pence system for simplicity.

Structure of the British System

The British system was built on three denominations:

• 1 pound (£1) = 20 shillings (s)
• 1 shilling = 12 pence (d)
• Thus, £1 = 240 pence

This may look awkward to modern eyes, but it allowed for flexible division. A pound divided by 2 gave 10 shillings. Divide it by 3, and you had 6 shillings 8 pence. Divide by 4, and it was 5 shillings. Dividing into halves, thirds, and quarters was natural, something decimals never quite manage.

The Guinea

The guinea was valued at 21 shillings, one shilling more than a pound. Originally struck from African gold imported by the Guinea Company in the 17th century, it soon became the preferred unit for gentlemen’s accounts.

Professional fees for doctors, lawyers, and artists were often quoted in guineas. A painting might cost “100 guineas,” a sum that carried connotations of prestige and refinement. The guinea thus existed not just as a unit of value but as a marker of social status.

For convenience, the Royal Mint also produced, at various times, half guinea and third guinea coins.

Trivia: Horse sales and certain luxury trades in Britain continued to be priced in guineas long after the coin itself vanished, preserving its aura of distinction.

The Crown and Other Coins

A crown was worth 5 shillings, exactly a quarter of a pound. Convenient for both accounting and coinage, the crown also carried ceremonial significance, being issued on special occasions. Half-crowns, worth 2 shillings and 6 pence, were equally common.

The sovereign, valued at one pound, and the half sovereign, valued at 10 shillings, were gold coins of great prestige. First issued under Henry VII in 1489, the sovereign became a symbol of the realm and a trusted unit in international trade. Their enduring place in British coinage reflected both wealth and stability.

Below these came the florin (2 shillings), the sixpence, the threepence (“thruppence”), the tuppence (two pence, immortalized as the price of a bag of bird seed in Mary Poppins), and the humble penny. Each had daily uses. The farthing, worth a quarter of a penny, allowed even the smallest purchases. For a child, a farthing meant sweets. For a laborer, it meant a cheap newspaper.

Everyday Use

The system may appear cumbersome on paper, but in practice, it was straightforward. Prices reflected reality: a loaf of bread for a few pence, wages in shillings, and rents in pounds. Shopkeepers made change quickly, aided by the fact that coins were distinct in size and feel.

Fractions that puzzle decimal systems—thirds, quarters, sixths—were effortless under £sd. A pound divided by 3 gave 6s. 8d., a neat figure in trade. Try dividing 100 decimal pennies into three and you end up with an infinite series of 3.333…

Historical Origins of £sd

The pound traces back to a weight of silver: the libra in Latin, hence the £ symbol. The abbreviation of “d” for penny comes from denarius, a Roman coin that circulated in Britain two millennia earlier. The shilling originally referred to the Roman solidus, a solid gold coin. Charlemagne’s monetary reform of 769 defined a schilling as one-twentieth of a pound, consisting of 12 denarii.

This set the stage for coinage throughout the Holy Roman Empire. Shillings and pence carried their lineage from medieval coinage.

Over centuries, the system adapted but retained its proportionality. It was not designed by committee but evolved through use, which made it robust.

Trivia: Nails in the U.S. are still measured in pennies, abbreviated d. This originated in 15^th-century England, where the unit referred to the cost to purchase 100 nails. A 6d nail meant you’d get 100 of them for six pence. Longer nails were more expensive and hence had a higher cost. Today, it’s simply a measure of the length. a 2d nail is 1 inch long, 6d nail is two inches long, a 16d nail is 3½ inches long, and a 60d nail is six inches long.

Conclusion

The pound-shilling-penny system embodied practicality, tradition, and social nuance. It could divide easily into fractions, it produced memorable coins like the crown, it supported social distinction with the guinea, and it allowed even the poorest to buy with the farthing. Decimal currency may be simple, but it is sterile. The old system was not just a way to count money; it was a way to live with it.