The Clactonian industry may have co-existed with the Acheulean industry, which used identical basic techniques but which also had handaxe technology; tools made by bifacially working a flint core.
Clactonian and Acheulean flint tools and human remains have been found dating to this stage.
The area was already famous for the finds of numerous Palaeolithic-era handaxes—mostly Acheulean and Clactonian artifacts, some as much as 400,000 years old—when in 1935/1936 work at Barnfield Pit uncovered two fossilised skull fragments.