This archaeological desk based assessment was commissioned on behalf of Blackleys Quarry, Great Leighs, Essex (TL 731 189), to assess the potential impact of an extension to the existing quarry within a proposed development area (PDA) of 56.4 ha. The following takes into account a study area of 3.0km radius in relation to the PDA. Set within arable farmland on London Clay, the PDA lies upon a topographic vantage point that overlooks the gravel valleys of the River Ter to the south and the River Brain to the north. These valleys are known for their prehistoric to Medieval archaeology, with 20th century defences also distributed across the rural landscape. The PDA lies almost adjacent to an established Roman road; however, it is also situated upon a clayland that has not yielded significant archaeological deposits, and an isolated soilmark identified through aerial survey within the Great Leighs Racecourse adjacent to the PDA has proven to be of a natural or recent origin. Whilst considered to be of a low archaeological potential, it is within this framework of previous and current land use and known archaeology that further evidence of past human activity is likely to be encountered within the PDA, especially those areas that have remained largely undisturbed by building foundations and services.