Born in Wiltshire, he was educated in Marlborough and worked in a puppet factory in the same town after he left school. He left his job in 1971 to work for the Southampton City Council Archaeology Unit, combining this with five seasons of excavations run by the British Museum at the Neolithic flint mines of Grimes Graves, Norfolk. He has since been an acknowledged expert on flint-knapping and has given many demonstrations around the country.
In the later 1970s he worked on excavations in Berkshire, Hampshire, Dorset, Wiltshire and the Isle of Wight for the Department of the Environment. In 1979 that section of the DOE became Wessex Archaeology, a non-profit organisation which is one of the biggest archaeological practices in the country. Phil Harding continues to work for Wessex Archaeology when not filming.