Roman Coins in Britain
When the Romans invaded Britain in 43 AD they brought with them a sophisticated coinage system that had been developing since the 4th century BC and which continued to develop until the fall of the Empire. From Claudius' invasion to the collapse of the empire in Britain in 410 AD a whole range of coins found their way into Britain.
Coins of the Early Empire
The initial coinage to enter Britain was that established during the reign of Emperor Augustus (27 BC-14 AD) consisting of the golden Aureus (worth 25 denarii), the silver Denarius (worth 4 sestertii), the copper alloy Sestertius (worth 2 dupondii), the Dupondius (worth 2 asses) and the As. The As was the basic unit, enough to buy a pound of bread or a litre of cheap wine, smaller fractions existed known as Semis and Quadrans.
One of the most widely used coins for the first 200 years of the Roman occupation was the Denarius. First struck in 211 BC it formed the backbone of the Roman system. However, over the next 400 years in the face of over spending the amount of silver in the coin was to drop considerably, from 95% in the days of late Republic to 50% by the reign of Septimius Severus (193-211 AD).
In response Emperor Caracalla struck a new coin in 214 AD, the silver Double-Denarius also referred to as the Antoninianus of 'Radiate Coin', so called as the emperor was depicted wearing a radiate crown, the head-dress of the divine.
In the 3rd century anarchy struck the empire, and between 218 AD and 284 AD no less than 37 emperors held imperial office. Emperors and usurpers alike paid for the support of large armies, consequently the Antoninianus was over struck. By the close of the century the coin contained only 2% silver.
By 295 AD the Antoninanus was an almost worthless, copper coin with a slight silvery wash and some of the smaller coins had fallen out of circulation. Emperor Diocletian looked to reform the whole system, the Antoninianus was removed and coinage was simplified, consisting of only the silver Argenteus/Follis (worth 100 old denarii), the golden Aureus and four smaller copper alloy fractions known as Nummus.
These coins did not initially reach Britain, the usurpers Carausius and Allectus (286-296 AD) had control of London mint and continued to strike radiate coins. Only when the empire was reunited did the new coins arrive in Britain.
Diocletian's reforms held until the 4th century when more political fragmentation and inward fighting dogged the empire. By the reign of Constantine (306-337 AD) further reform was needed. The Argenteus was removed and new coins introduced, the gold Solidus and the silver Siliqua along with other multiples and fractions.
This time there was no sudden decline in the silver and despite some reforms to bronze coinage many of Constantine's reforms held until the fall of the empire. In Britain the usurper Magnentius briefly issued his own coins between 350-353 AD, however these are not common finds as they were quickly removed after the fall of Magnentius.
Return of the Barter Economy
When the Romans left Britain, the monetary system dissolved away with it and a barter system returned to the island. It would not be until the 6th century that currency began to circulate again in Britain.