After Harding left school he worked in a puppet factory in Marlborough, until he became a full-time archaeologist in 1971. He worked initially for the Southampton City Council Archaeology Unit, combining this with five seasons of excavations (1972–1976) run by the British Museum at the Neolithic flint mines of Grimes Graves, Norfolk. He has since become an acknowledged expert on flint-knapping and is skilled in lithic reduction using both percussive techniques and pressure flaking, in which instead of striking the flint with blows, pressure is exerted on the edges to shape the tool.