This data set comprises plant species, habitat and land cover types, and major biota present, collected during an ecological survey of marginal uplands in the English county of Cumbria, using standardised survey methods. The survey was undertaken by the Institute of Terrestrial Ecology (a forerunner of the Centre for Ecology & Hydrology) in 1978 within a stratified random set of sites. In total, up to 262 plots were surveyed from within 52 x 1km squares.