This paper presents 21 new radiocarbon dates for Iron Age burials excavated at Wetwang Slack, East Yorkshire, including three chariot burials. The dates are analysed using a Bayesian approach, along with previous dates from the cemetery and from other chariot burials in the region. The model suggests that regular burial at Wetwang spanned the third and earlier second centuries cal BC, a shorter period than once thought, whilst the chariot burials all belong to a short-lived horizon centred on 200 cal BC. The dating of brooch types present in the burials is also reassessed. Our results imply that brooches of La Tène D form appeared in Britain in the later second century cal BC, in line with Continental evidence, but reinforcing the void in the later Iron Age sequence revealed in a recent study of decorated metalwork. Both this apparent gap and the end of the classic East Yorkshire mortuary tradition may well be manifestations of the more general changes that swept across Europe at this period, ushering in the new forms of political organization and social practices that define the Late Iron Age.