Palaeoclimatic data provide the quantitative information and context required for the study and attribution of natural- and anthropogenic-forced climatic variability. If our society is to appropriately address the future challenges of climate change, it is of vital importance that we know how the climate of the United Kingdom (UK) has varied in the past. Only with this information will it be possible to formulate effective policy and critically evaluate the performance of the Earth system models that increasingly underpin UK climate policy. Currently proxy-specific limitations severely constrain the number of reliable temperature or precipitation reconstructions for these islands. This is especially true of numerically verifiable reconstructions of late Holocene (<2kya) climate. Remarkably, despite a long established tradition of palaeoclimatology, we have not established, with any confidence, the frequency of seasonal extremes, or indeed the levels of temperature and precipitation of the Roman, Mediaeval, or "Little Ice Age" periods; and importantly, we cannot therefore make comparisons with recent climate. As a consequence, policy makers, researchers and the public are forced to rely upon lower-confidence reconstructions or outdated, uncalibrated low-frequency records based upon anecdotal evidence. This is wholly inappropriate for both modern numerical analyses and robust evidence-based decision making. Our new, but rigorously tested method, is based upon the stable carbon and oxygen isotope analysis of precisely-dated oak tree-rings. These data are capable of capturing past climatic variability (both temperature and precipitation) with a high degree of numerical accuracy. We can therefore address this research gap for the UK and other under-represented, temperate mid-latitude regions. This project will develop 2000 year numerically verifiable reconstructions of summer temperature and precipitation, with defined confidence intervals. Such data are urgently required by the research community and will be incorporated into national and continental-scale palaeoclimate composites, enhancing their regional relevance and reconstructive skill. We will deliver a quantitative reference climatology that will mark a step-change in UK palaeoclimatology, moving from reliance upon seminal, but outdated research (e.g. Lamb 1966), to a new numerical and tightly constrained understanding of past climate.