The British Iron Age is a conventional name in the archaeology of Great Britain referring to the prehistoric and proto-historic phases of the Iron-Age culture of the main island and the smaller islands, typically excluding Ireland. The parallel phase of Irish archaeology is termed the Irish Iron Age, and similarly locally defined Iron Ages exist for many regions of Europe, such as the Danish Iron Age. The Iron Age is not an archaeological horizon of common artefacts, but is rather a locally diverse cultural phase. Whatever is said of the British Iron Age is not necessarily transferable to any other, and vice versa, except for the common preference for the use of iron.

The various Iron Ages have no common set of dates. The British Iron Age lasted in theory from the first significant use of iron for tools and weapons in Britain to the Romanisation of the southern half of the island. The Romanised culture is termed Roman Britain and is considered to supplant the British Iron Age. This terminology should not be construed to mean that Roman Britain and the Romans there and elsewhere were not in the Iron Age. Although the beginnings of Iron Ages are generally well-defined by the widespread use of iron tools, the endings have no such physical basis of definition. By convention the Iron Age ends when a more salient basis for characterising the culture becomes available, such as Roman occupation. The Irish Iron Age was ended by the rise of Christianity there.

The tribes populating the island belonged to a broadly Celtic culture. The British language is recognised as one of the Celtic languages. It does not mean that the British identified themselves as Celts.

The proposition that some Iron Age cultures of Europe share a substantial cultural unity based on a common ethnicity, specifically termed Celtic, has for the most part lost credibility. Critics claim that a unity has been an artificial creation a priori on little or no genuine evidence.

The controversy continues with as yet no resolution acceptable to the mainstream of scholars. Nevertheless, the Celtic nature of the language spoken at that time is not in dispute.

Periodisation

At present over 100 large Iron-age sites have been excavated dating from the 8th century BC to the 1st century BC, overlapping on the Bronze Age in the 8th century BC. Hundreds of radiocarbon dates have been acquired and have been calibrated on four different curves, the most precise being based on tree ring sequences.

The precision of the dates in this first millennium BC does not allow a periodisation based on the radiocarbon dates. The range of any one radiocarbon date at one Standard deviation; that is, at 68% probability of the historical date being within the range, is in the order of a few hundred years. Many schemes have been proposed based on sequences of pottery and other artefacts. The following scheme summarises a comparative chart presented in a recent book by Barry Cunliffe:

• Earliest Iron Age. 800-600 BC. Parallel to Hallstatt C on the continent.

• Early Iron Age. 600-400 BC. Hallstat D and half of La Tène I.

• Middle Iron Age. 400-100 BC. The rest of La Tène I, all of II and half of III.

• Late Iron Age. 100-50 BC. The rest of La Tène III.

• Latest Iron Age. 50 BC - 100 AD.

The end is extended into the early Roman Empire under the theory that Romanisation required some time to effect. In parts of Britain that were not Romanised, such as Scotland, the period is extended a little longer, say to the 5th century. The geographer closest to 100 AD is perhaps Ptolemy. Pliny and Strabo would already have written, but Ptolemy gives the most detail (and the least theory).

Archaeological evidence

Attempts to understand the human behaviour of the period have traditionally focused on the geographic position of the islands and their landscape, along with the channels of influence coming from continental Europe.

During the later Bronze Age there are indications of new ideas influencing land use and settlement. Extensive field systems, now called Celtic fields, were being set out and settlements becoming more permanent and focused on better exploitation of the land. The central organisation to undertake this had been present since the Neolithic period but it was now being targeted at economic and social goals and in taming the landscape rather than in building large ceremonial structures such as Stonehenge. Long ditches, some many miles in length, were dug with enclosures placed at their ends. These are thought to indicate territorial borders and a desire to increase control over wide areas.

By the 8th century BC, there is increasing evidence of Great Britain being closely tied to continental Europe especially in the south and east. New weapon types appeared with clear parallels to those on the continent such as the Carp's tongue sword, complex examples of which are found all over Atlantic Europe. Phoenician traders probably began visiting Great Britain in search of minerals around this time, bringing with them goods from the Mediterranean. At the same time, northern European artefact types reached eastern Great Britain in large quantities from across the North Sea.

Within this context, the climate became considerably wetter forcing the Bronze Age farmsteads which had grown on lowland areas relocate to upland sites.

Defensive structures dating from this time are often impressive, for example the brochs of northern Scotland and the hill forts that dotted the rest of the islands. Examples of hill forts include Maiden Castle, Dorset and Danebury in Hampshire. Hill forts first appeared in Wessex between 550 and 400 BC in a simple univallate form and often connected with the earlier enclosures attached to the long ditch systems. Few hill forts have been substantially excavated in the modern era, Danebury being a notable exception but it appears that they were used for domestic purposes with examples of food storage, industry and occupation being found within their earthworks. They may have been only occupied intermittently however as it is difficult to reconcile permanently occupied hill forts with the lowland farmsteads and their roundhouses found during the twentieth century such as at Little Woodbury and Rispain Camp.

The presence of hill forts is possibly because of greater tension between better structured groups, although there are suggestions that in the latter phases of the Iron Age they existed simply to indicate wealth. Alternatively, they may have served as wider centres used for markets and social contact. Either way, during the Roman occupation the evidence suggests that as defensive structures they proved to be of little use against concerted Roman attack. Some continued as settlements for the newly conquered Britons. Some were also reused by later cultures, such as the Saxons, in the early Medieval period.

The people of Iron Age Britain

Demography

The Roman historian Tacitus described the Britons as being descended from people who had arrived from the continent, comparing the Caledonians (in modern-day Scotland) to their Germanic neighbours; the Silures of southern Wales to Iberian settlers; and the inhabitants of south east Britannia to Gaulish tribes. This migrationist view long informed later views of the origins of the British Iron Age and indeed the making of the modern nations. Linguistic evidence inferred from the surviving Celtic languages in northern and western Great Britain appeared to back this idea up and the changes in material culture which archaeologists observed during later prehistory were routinely ascribed to a new wave of invaders.

By the 1960s this view had fallen from favour as it was argued that changes in language and artefact types could not necessarily be attributed to large, long distance population movements. Ideas can be transported more easily than people and can account for many changes in the archaeological record, and for the presence of Celtic languages in Britain. The numerous finds of swords and other weaponry were originally attributed to a warlike society but are now interpreted as items of social status, perhaps given as diplomatic gifts between tribes

There was certainly a large migration of people from central Europe westwards during the early Iron Age but whether or not people from this movement actually reached Great Britain in significant enough numbers to constitute an invasion is in question. The arrival in Kent of the Belgae in the 1st century BC still requires explanation under any non-invasionist theory however.

Population estimates vary but the number of people in Iron Age Great Britain could have been three or four million by 150 BC with most concentrated densely in the agricultural lands of the south. Settlement density and a land shortage may have contributed to rising tensions during the period.

Early in the Iron Age, the widespread Wessex pottery of southern Great Britain such as the type style from All Cannings Cross may suggest a consolidated socio-economic group in the region. However, by 600 BC this appears to have broken down into differing sub-groups with their own pottery styles. Between c. 400 and 100 BC there is evidence of emerging regional identities and a significant population increase.

Ptolemy's Albion

Claudius Ptolemy described Iron Age Britain at the beginning of Roman rule, but incorporating material from earlier sources. Although the Pretanic Isles had been known since the voyage of Pytheas and Britannia was in use in Strabo and Pliny, Ptolemy uses the earlier Albion, known from as early as the Massaliote Periplus.

Iron Age beliefs in Britain

The Romans recorded a variety of deities worshipped by the people of north western Europe. Barry Cunliffe perceives a division between one group of gods relating to masculinity, the sky and individual tribes and a second, female group of goddesses with associations with fertility, the earth and a universality that transcended tribal differences. Wells and springs had female, divine links exemplified by the goddess Sulis worshipped at Bath. In Tacitus's Agricola (2.21) he notes the similarity between both religious and ritual practices of the pre-Roman British and the Gauls.

Religious practices revolved around offerings and sacrifices, sometimes human but more often involving ritual slaughter of animals or the deposition of metalwork, especially war booty. Weapons and horse trappings have been found in the bog at Llyn Cerrig Bach on Anglesey and are interpreted as votive offerings cast into a lake. Numerous weapons have also been recovered from rivers especially the Thames but also the Trent and Tyne. Some buried hoards of jewellery are interpreted as gifts to the earth gods.

Disused grain storage pits and the ends of ditches have also produced what appear to be deliberately placed deposits including a preference for burials of horses, dogs and ravens. The bodies were often mutilated and some human finds at the bottom of pits such as those found at Danebury may have had a ritual aspect.

The priesthood of this religion was the Druids. Caesar's texts tell us that they were a religious elite with considerable holy and secular powers. Great Britain appears to have been the seat of the Druidic religion and Tacitus' account of the later raid on Anglesey led by Suetonius Paulinus gives some indication of its nature. No archaeological evidence survives of Druidry although a number of burials made with ritual trappings and found in Kent may suggest a religious character to the subjects.

Overall the traditional view is that religion was practised in natural settings in the open air. Several sites interpreted as Iron Age shrines however seem to contradict this view which may derive from Victorian and later Celtic romanticism. Sites such as at Hayling Island in Hampshire and that found during construction work at Heathrow airport are interpreted as purpose-built shrines. The Hayling Island example was a circular wooden building set within a rectangular precinct and was rebuilt in stone as a Romano-British temple in the first century AD to the same plan. The Heathrow temple was a small cella surrounded by a ring of postholes thought to have formed an ambulatory which is very similar to Romano-Celtic temples found elsewhere in Europe.

Death in Iron Age Great Britain seems to have produced different behaviours in different regions. Cremation was a method of disposing of the dead although the chariot burials and other inhumations of the Arras culture of East Yorkshire, and the cist burials of Cornwall, demonstrate that it was not ubiquitous. In fact, the general dearth of excavated Iron Age burials makes drawing conclusions difficult. Excarnation has been suggested as a reason for the lack of burial evidence with the remains of the dead being dispersed either naturally or through human agency.

The Economy of Iron Age Britain

Trade links developed in the Bronze Age and beforehand provided Great Britain with numerous examples of continental craftsmanship. Swords especially were imported, copied and often improved upon by the natives. Early in the period Hallstat slashing swords and daggers were a significant import although by the mid sixth century the volume of goods arriving seems to have declined, possibly due to more profitable trade centres appearing in the Mediterranean. La Tène culture items (usually associated with the Celts) appeared in later centuries and again these were adopted and adapted with alacrity by the locals.

There also appears to have been a collapse in the bronze trade during the early Iron Age, which can be viewed in three ways:

1. Steady Transition; the development of iron parallel to a diminishing bronze system

2. Rapid Abandonment; iron undermines bronze and takes over its social function

3. Bronze Crisis; severe reduction in the supply of bronze allows the iron to replace it

Exports certainly included British weaponry, which has been found on the continent, although this may represent the diplomatic links discussed above. Hengistbury Head in Dorset had a large natural harbour that was an important port for the import and export of goods with the Roman world. The products which Strabo, the Greek geographer recorded describe Great Britain as providing "grain, cattle, gold silver, iron, hides, slaves and hunting dogs" .

With regard to animal husbandry, cattle represented a significant investment in pre-Roman Britain as they could be used as a source of portable wealth as well as providing useful domestic by-products such as milk, cheese and leather. In the Later Iron Age an apparent shift is visible, revealing a change in dominance from cattle rearing to that of sheep. Economically, sheep are significantly less labour intensive, requiring fewer people per animal.

Whilst cattle and sheep dominate the osteo-archaeological record, evidence for pig, ox, chicken and dog is widely represented. Interestingly, the environmental remains are absent of hunted game and wild species as well as fresh and sea water species, even in coastal communities.

A key commodity of the Iron Age was salt, used for preservation and the supplementation of diet. Whilst difficult to find archaeologically, some evidence does exist. Salterns, in which sea water was boiled to produce salt, are prevalent in the East Anglia fenlands. Additionally, Morris notes that some salt trading networks spanned over 75 km.

Representing an important political and economic medium, the vast number of Iron Age coins found in Great Britain are of great archaeological value. Some, such as gold staters, were imported from mainland Europe. Others such as the cast bronze (potin) coins of south-east England are clearly influenced by Roman originals. The British tribal kings also adopted the continental habit of putting their names on the coins they had minted, with such examples as Tasciovanus from Verulamium and Cunobelinos from Camelodunum identifying regional differentiation. Hoards of Iron Age coins include the Silsden Hoard in West Yorkshire found in 1998. Of examples that were entirely minted locally, a large hoard from the Corieltauvi tribe was found in Leicestershire in 2002 and consisted of 5292 coins from a period of 30–40 years of ritual deposition. Importantly, this represents the most northernly example of coinage in Iron Age Britain, as areas north of this did not use this unified value system.

The expansion of the economy throughout the period, but especially in the later Iron Age, is in large part a reflection of key changes in social and status expression.

The end of Iron Age Britain

Historically speaking, the Iron Age in southern Great Britain ended with the Roman invasion. Clearly the native societies were not instantaneously changed into toga-wearing, Latin-speaking provincials, though some relatively quick change is evident archaeologically. For example, the Romano-Celtic shrine in Hayling Island, Hampshire was constructed in the AD 60s–70s., whilst Agricola was still campaigning in Northern Britain (mostly in what is now Scotland), on top of an Iron Age ritual site. Rectilinear stone structures, indicative of a change in housing to the Roman style are visible from the mid to late first century AD at Brixworth and Quinton.

In areas where Roman rule was not strong or was non-existent, Iron Age beliefs and practices remained, but not without at least marginal levels of Roman, or Romano-British influence. The survival of place names, such as Camulodunum (Colchester), from the native language is evidence of this.

Re-creation

In 1978 a BBC TV project, Living in the Past, attempted to re-create life in an English Iron Age village with a group of 15 volunteers over a period of thirteen months.