coinage and currency in Roman Britain

Although coinage changed significantly during the 370 years or so of Roman Britannia, in theory imperial Rome’s currency always consisted of a tri-metallic system (gold, silver and bronze), composed of interchangeable denominations of different monetary values. Low-value small-change denominations are most common from archaeological excavations, whereas higher value coins are more often found in hoards.

In 215, the emperor Caracalla introduced a new silver coin that seems to have been valued at 2 denarii. This is often referred to as the ‘antoninianus’, though the literary and historical evidence indicates it was known as the radiate instead (from the sun’s rays on the crown worn by the obverse portrait). The radiate replaced the denarius from the 240s, but quickly became debased and was issued in very large quantities for most of the rest of the 3rd century. Radiates and their irregular copies are very common finds from Romano-British settlements.

Diocletian’s monetary reforms around 294 replaced the previous coinage with a new currency system, including a silver denomination (argenteus), as well as a new suite of low value copper-alloy denominations. Later reforms during the 4th century saw the introduction of new gold and silver denominations (solidus, miliarensis and siliqua), as well numerous reforms of the bronze coinage. The last Roman coins to enter Britain in any quantities were struck 395 to 402, after which date the mints in Gaul and Italy suddenly and almost completely ceased striking coins.