Which disaster, resulting in the death of one third of the English, Scottish, and Welsh population, was one of the worst in British history?

The Black Death, a devastating pandemic caused by the bacterium Yersinia pestis, swept across Europe in the mid-14th century, and Britain was hit incredibly hard. While other plagues certainly occurred throughout British history, none reached the sheer scale and mortality rate of the Black Death. It arrived in England around 1348 and, within just a few years, wiped out an estimated one-third to one-half of the population of England, Scotland, and Wales. The social and economic consequences were profound, leading to labor shortages and significant shifts in the feudal system. While "The Great Mortality," "The Great Pestilence," and "The Great Plague" sound plausible, they are either less specific terms or refer to other outbreaks. The term "Great Plague" is most often associated with the outbreak in London in 1665, which was terrible but didn't have the same nationwide impact or mortality rate as the Black Death two centuries earlier. The sheer scale of death and societal disruption caused by the Black Death makes it a uniquely devastating event in British history.