Roman coins circulated in Britain from Celtic times, even before the conquest by the emperor Claudius in A.D.43. Following the occupation normal Roman coins were then used for some 250 years before Britain had its own mint. However, the Romans issued many coins with reference to Britain, including gold coins of Claudius showing a triumphal arch inscribed DE BRITANN, commemorating the conquest.
The initial phase of the conquest established a frontier from roughly the Severn Estuary to the Wash. The Britons were mostly allowed to retain their rulers, serving as client-kings of the Romans. Unfortunately for the Britons, Roman ambitions did not stop there and after a series of punitive raids beyond the frontier, the suppression of the Boudiccan rebellion and a period of consolidation which saw Roman rule extended into Wales, a decision was made to occupy the whole of the country. Accordingly Cnaeus Julius Agricola, governor of Britain, was given the task of subduing the native tribes, which he did with typical Roman thoroughness in a bloody campaign that lasted some seven years, from A.D.77-83.
Mintmark: AVGOB (Augusta Obryziacum)
That Britain did not fall victim to another barbarian invasion after being denuded of its garrison is a tribute to a system of foederati. which at first worked extremely well. This entailed settling barbarian tribes in frontier areas liable to attack, thus two Germanic tribes, the Votadini and the Damnoni were allocated to North Wales and the north of England respectively and other mercenaries were employed in Kent. North Saxon mercenaries were also employed against a new attack by the Picts. Stilicho, a Vandal general in the army of the emperor Honorius, came to Britain late in the fourth century to organise the country's defences. His efforts were negated a few years later when in A.D. 407 the legions in Britain declared one of their number, Constantine, as emperor and invaded Gaul to lay claim to the throne, chosen, apparently, because of his name and it was the centenary of Constantine the Great's elevation. Following his eventual defeat in A.D. 411, the garrison of Britain was never replenished and when a deputation from Britain was sent to Rome in A.D. 446 it carried a letter with the famous phrase "The barbarians drive us into the sea and the sea drives us back to the barbarians". No help was forthcoming. A few years later a foederati king called Vortigern invited the Saxons to occupy the south and effectively Roman rule was at an end. The Romano-British tribes were gradually pushed
back into Wales, Devon and Cornwall and by the late 7th Century all of England had come under the control of the invaders.
Carausius & Allectus AD 286-296
London Mint Coins A.D. 296-325
THE ROMAN COINAGE SYSTEM
From the time Augustus (27 B.C.-14 A.D.) until the middle of the 3rd Century, the Roman monetary system consisted of a number of denominations struck in four different metals, gold, silver, orichalcum (a kind of brass) and copper. During the latter half of the 3rd century onwards coins of gold and a silver-washed bronze alloy were issued. Silver coins made their appearance as part of Diocletian's reforms late in the 3rd Century, and again during the reign of Constantine, being produced in substantial quantities from about AD 350 until the joint reigns of Arcadius and Honorius at the end of the Century. Thereafter, silver coins are quite scarce.
An important point to remember concerning Roman coins is that after AD 214 we are mostly unaware of what the Romans called the various new denominations introduced. Most names in common use are those allocated to them by modern numismatists.
Very often these coins are listed with a set of relative values ascribed to them, for example the gold coin or aureus is quoted as being worth 25 silver denarii. A reading of Roman documents shows that this is a modern interpretation. The actual system is more complicated.
What needs to be understood is that the medium of exchange was the base metal coinage and that gold and silver were only for the convenience of storing or transporting large sums of money. Only when silver coins had themselves become so debased they were virtually copper did they supplant the base metal coins for transactions. All prices were therefore quoted in terms of the brass sestertius. which had a nominal value of a quarter of a denarius. and all payments in the market place were made using that coin or one of the smaller brass or copper denominations. Before spending a gold or silver coin it had first to be exchanged with the money-changers for its current value in these base metal coins. You could also buy gold and silver coins from the money-changers. Either way you paid a premium, rather like today when obtaining foreign currency.
What the table below shows therefore, is what is thought to be the approximate relative value of the various denominations, but there is no certainty of their correctness or for how long a period they applied.