As far as insular Celtic art is concerned, the problem of establishing firm dates is even more difficult than on the Continent, since even Mediterranean imports are lacking as chronological markers until late on. In Britain and Ireland a new art style, related to the styles of continental Europe, appeared at least as early as the beginning of the third century BC (Raftery 1983, 1984; Stead 1985, 1991; Megaw and Megaw 1986). A number of isolated finds in eastern England, and Ulster, notably decorated shields and sword scabbards of basically early La Tene form, exhibit elements of both the ‘Vegetal’ and ‘Sword’ styles (Figure 20.5). Only in north-east Yorkshire, however, is such material found in closed contexts, notably in the rich graves of the so-called ‘Arras culture’ which include cart or chariot burials similar but not identical to those of the Marne (Dent 1985; Stead 1979, 1991). Despite Indications of the influence of continental styles and burial customs, there is, however, no such certain evidence for major groups of new settlers. Links between Britain and Ireland seem highly probable and direct links with the Continent from both areas possible. New art styles may represent the Introduction of new belief systems and certainly, in view of the evidence for a continuity of settlement patterns in Britain from the previous Late Bronze Age, one may envisage a process whereby native communities adopted, through the agency of a few foreign - or at least foreign-trained - missionaries and craftworkers, a new range of symbols of spiritual and temporal power.
From the second century BC until the occupation of southern Britain by the Romans in the mid-first century AD a number of regional stylistic groups develop, although it is not until the late first century BC that there are firm archaeological contexts, such as datable graves or settlements, for such specialized classes of objects as horse harness or engraved bronze mirrors (Figure 20.1(7)). In the later Iron Age of Ireland, untouched by Roman settlement but exhibiting sporadic trading contacts with the new overlords of Britain from the first to the fifth centuries AD, the fine products of the ‘Ultimate La Tene’ period lack datable context but are not likely to be much later than the second century AD.