This article examines the role of a range of large settlements in late Iron Age and early Roman southern Britain (c. 100 BC–AD 70) conventionally described as oppida. After reviewing current perspectives on the function and chronology of British oppida, new insights are provided through the statistical analysis of assemblages of brooches and imported ceramics at a broad sample of sites. Analysis of material culture reveals distinct similarities and differences between several groups of sites, often transcending regional traditions and supposed tribal boundaries. This patterning is primarily explained by the emergence of new forms of political organization prior to Roman annexation, particularly the creation of the Southern and Eastern Kingdoms.

Since the establishment of the Portable Antiquities Scheme, the systematic reporting of metal-detected finds in England and Wales has increased our knowledge of distribution patterns and complemented the evidence from assemblages uncovered by conventional excavation. The large number of Roman metal small finds documented, particularly brooches, now allows for a quantitative comparison between those recovered through excavation and those discovered by metal-detecting. This study shows that certain artefact morphologies are more easily detected than others, resulting in differential rates of representation in the archaeological record. It is suggested that similar biases can be seen in artefacts from other periods. This has important consequences for anyone wishing to use metal-detected material in synthetic studies.

Regional and temporal patterns in brooch use in Britannia are studied, confirming and challenging ‘received wisdoms’ about ‘regionality’. The complexity of the ‘Fibula Event Horizon’ is brought into sharp focus; a similarly complex and unexplained ‘Fibula Abandonment Horizon’ is also clearly demonstrated. Conclusions are insensitive to assumptions about use-life. Detailed analysis for the family of trumpet brooches casts light on hitherto unappreciated features of ‘regionality’. Comparison with continental data suggests the British temporal patterns may be reflecting a wider north-western province pattern. Under-studied aspects of bias in metal-detected finds and their implications for studies of this kind are noted. The Supplementary Material available online (http://journals.cambridge.org/bri) contains tabular information on the data used in the study and additional analyses that support some of the assertions made in the main text.