The Neolithic in Britain saw the first appearance of domestic plant and animal resources, pottery, polished stone axes, monuments, and new house structures. With the introduction of domesticates and associated subsistence strategies, the Neolithic represents a significant change in human–environment interaction. Other changes have been observed in the palynological record of Britain in the early fourth millennium cal BC, including the elm decline, and archaeologists and paleobotanists have long discussed the degree of human involvement in this. This paper presents the first Bayesian statistical analysis of the elm decline using the case study of the east of Yorkshire and Humberside and key sites in west Yorkshire, and evidence for the last hunter-gatherer Mesolithic material culture and the first Neolithic material culture record. This region is critical because it is the only area of Britain and Ireland where we have robust and accurate published estimates for the timing of the latest Mesolithic activity and timing for the earliest Neolithic activity. Unpacking this perceived chronological correlation between the elm decline and the start of the Neolithic is critical to understanding the scale of human–environment modification at this time, and the nature of the first Neolithic societies in Britain.