During the Second World War Piggott worked as an air photo interpreter and was posted to India where he spent time studying the archaeology of the sub-continent, eventually leading him to write the books Some Ancient Cities of India (1946) and Prehistoric India (1950).
After the war he went to Oxford to study the work of William Stukeley, but in 1946 was offered the Abercromby Chair in Archaeology at Edinburgh University (now part of the School of History, Classics and Archaeology), in succession to Gordon Childe.