Celtic currency of Britain

The Celtic currency of Britain were the various items and coins used as currency between approximately 200 BC and AD 60. The earliest currency consisted of various forms of iron bars. Coins were first imported in large numbers in around 150 BC and domestic minting began around 100BC. Coin production was largely ended by the Roman conquest of Britain, first by the Claudian invasion of AD 43 and later by the Defeat of Boudica in AD 60 or 61. Cast coins may have been produced for a few more years around Hengistbury Head. Exact dating of coins often changes in the light of new research.
Coin use is usually divided into a core area which covers the home counties as well as parts of Oxfordshire, Northamptonshire and Cambridgeshire. This was surrounded by a periphery of coin using groups some of which, the Corieltauvi, Durotriges, Dobunni and Iceni, appear to have minted their own coinage. The coins in the core area are generally attributed to the Atrebates and Cantii in the areas south of the Thames and the Trinovantes and Catuvellauni to the north.
The archaeological record may be distorted by cases of the deliberate falsification of find spots. Historically this falsification may have been driven by farm-workers wanting to hide that they had taken the coins from their employer's land. More recently, false provenances have been produced to hide the source of coins looted by metal detectorists such as the mass looting of the Wanborough Temple site.

Iron bar and other non-coinage currency

The first currency in Britain appears to have been iron currency bars first appearing around 200BC. Currency bars have been found in four forms known as sword-shaped, spit-shaped, plough-shaped, and bay-leaf-shaped. It has been suggested that these shapes were used to show the origin of the bars. The bars generally weigh between. Spit-shaped bars are the most commonly found, representing half of all finds. Sword-shaped bars make up another 40 percent.
What appears to be iron bar currency was mentioned in Julius Caesar's Commentarii de Bello Gallico. There are variances in the surviving texts, meaning that it is possible the original text was referring to iron ring money. However, iron bar currency is considered more likely in the light of archaeological discoveries.
Historically it has been claimed that gold rings were used as currency, but improved dating has rendered this claim unlikely. John Lesley, writing in the 16th century, claimed that leather money had been issued in Scotland in the second century BC. No evidence for this claim has been found.

Coins

Names

The original names of British Celtic coins are unknown.
Modern researchers have given coins whether inscribed or uninscribed various names. Gold coins are described as staters or quarter staters, with the name deriving from Greek coins. Gold staters generally weighed between. Quarter staters, as their name suggests, had about a quarter of the weight of gold staters. A few gold coins without clear weight relationships to staters are sometimes called gold fractions.
Silver coins are described as staters, units, half units and minims. Units generally weighed between, with half units about half the weight of units. Minims covers the various silver coins weighing less than.
Copper alloy coins are described as staters, quarter staters, and units with cast staters and potins being considered separately.
More specific names for individual coin types generally consist of catalog numbers, although in some cases simple descriptions are used. Over the decades various catalogs have been compiled, with Van Arsdell's 1989 catalog being the most popular. Overlap between catalogs does, however, mean that a coin can have as many as seven different names.

Methods of manufacture

Most British Celtic coins were struck although a few were cast.
The exact details of the method by which struck coins were struck remains unclear. It is thought most likely that struck coins were made by a four-step process. First, a fairly exact amount of metal would be weighed out in the form of powder or nugget. The metal would then be placed in a clay mould and heated to form a blank. Examples of these moulds have been found in archaeological excavations. The blank would then be flattened before finally being placed between two dies and struck. The lower die would be concave in order to hold the blank in place while the upper die would be convex. The dies were frequently larger than the blanks being struck, resulting in only part of the design appearing on the coin. Experimental archaeology suggests that a lower die could be expected to last for up to 10,000 strikes depending on the level of wear deemed acceptable. Upper dies seem to have a far greater range of lives, with usable lives ranging from just over 100 strikes to nearly 8,000 being reported. Combining archaeological evidence with historic records suggests ancient coin producers could get as many as 47,000 strikes out of an individual die.
It is possible that in some cases, instead of moulds being used, the metal would be melted and poured onto a flat surface.
A number of coins from the period consisting of a base metal core and a precious metal coating have been found. These would have been made by coating the base metal with a thin layer of precious metal, then striking the blank. While these coins for the most part appear to have been straightforward forgeries, some appear to have been struck using the same dies as non forgeries, making their status less clear.
In the case of cast coins, a series of clay moulds joined by runners were used. The patterns on the coins were produced by pressing a pattern into the clay or, in simpler cases, scratching lines in it. Molten metal would then be poured into the moulds. Once the metal had cooled, the moulds would be broken to access the coins.

Imported coins

The earliest coins to appear in the British archaeological record are third or fourth century BC Carthaginian bronzes, although it seems unlikely that they were used as currency. It is possible that these coins entered Celtic society as payment to mercenaries by Carthage and Syracuse. Other coins from the end of the third century and start of the second century BC have been found but there is no evidence for their use as currency and the situation is complicated by contamination by modern losses. Post antiquity a direct trade route for Greek coins into Britain has existed since the creation of the Levant Company in the late 16th century.
Around 150BC Gallo-Belgic staters started being imported into Britain. These coins followed designs ultimately derived from the staters issued by Philip II of Macedon and were made from gold. Philip's staters featured on the obverse the head of Apollo wearing a wreath. On the reverse they carried an image of a Biga chariot being pulled by two horses and carrying a figure wielding a whip. Six series of Gallo-Belgic staters issues are known as A through to F with subtypes such as AA and AB. Of these it is C through to F that would have the most impact on later British coin designs. The minting of these coins came to an end with the Roman conquest of Gaul. It is possible that at least some of these coins were produced in Britain instead of being imported. A die for striking Gallo Belgic A coins has been found in Bredgar, Kent but it isn't clear if it was used for official strikes or forgeries.
Along with the Gallo-Belgic stater series other coins from the continent have been found in Britain. Ambiani coins have been found along the south coast of the West Country, possibly arriving there as the result of trade across the English Channel.

Potins

appear to have been the first coins made in Britain dating from the end of the second century BC. They appear to have circulated mainly in Kent and were based on coins issued by Massalia. Various other potins were issued with production ending around 50BC. These coins were cast rather than struck. Although potins were around at the same time as the first British gold coins they aren't found together which suggests they served a different role in society. Potins continued to circulate for some time after the Roman conquest of Britain and they have been found in burials dating to the late Roman period.

Uninscribed staters

The first known British stater was based on the Gallo-Belgic C stater and appears to have been made by melting down said staters and re-striking them. It is referred to as the British A stater or the Westerham and Ingoldisthorpe stater, and was probably made shortly after 100BC. The coin is often credited to the Atrebates kingdom but this is uncertain.
At much the same time or shortly afterwards, a range of uninscribed British staters was produced by various groups, with inscribed coins not appearing until after 50BC. As with the Gallo-Belgic staters, these coins have been divided into a number of series which have in turn been divided into various subtypes.

Series	Alternative names	First minted	Minted by	Mainly found	Based on	Image
A	Westerham and Ingoldisthorpe, Westerham	100BC or shortly after	Atrebates?		Gallo-Belgic C
B	Chute	60-50BC	Durotriges?	Dorset, Wiltshire and Somerset	Gallo-Belgic C
C	Yarmouth			Hampshire, Isle of Wight	British A
D	Cheriton	50BC-30BC		Hampshire, Isle of Wight	British B
F	Clacton	100BC or shortly after
G	Clacton	100BC or shortly after
H	North-east coast	70BC	Corieltauvi		Gallo-Belgic C
I		70BC	Corieltauvi		Gallo-Belgic C
J	Norfolk wolf	50BC	Iceni		Gallo-Belgic E
K	South Ferriby	40BC	Corieltauvi
L	Whaddon Chase	50BC	Cassivellaunus?	Hertfordshire, Buckinghamshire, Bedfordshire and Essex
N	Freckenham	40BC	Iceni
Q		50BC			Gallo-Belgic F
R			Dobunni		British Q?

During the Gallic Wars the weight of gold staters being issued fell slightly. At the same time silver coinage started to be issued in some areas.