John Harald Westergaard was born on 13 October 1927 in Putney, London, to Otto and Inger Westergaard; his parents were Danish and his father was a civil engineer. In 1938, with his parents about to divorce, Westergaard moved to Denmark with his mother and was sent to boarding school in Copenhagen; his experiences under Nazi occupation and his mother's attachment to the Danish resistance movement during the Second World War encouraged an opposition to authority and a belief in socialism. He was briefly a censor in the British Army of the Rhine and then completed a sociology degree at the London School of Economics (LSE), graduating in 1951. He was a researcher to Ruth Glass at University College London, before moving to the University of Nottingham for the 1955–56 year. He then returned to the LSE as a lecturer, and secured promotion to a readership in sociology in 1970. In 1975, he was appointed as Keith Kelsall's successor to the Chair in Sociological Studies at the University of Sheffield. He retired in 1986 amid funding cuts and declining student numbers which had led to the sociology honours degree course falling into abeyance at Sheffield. His early retirement – and that of Eric Sainsbury (Chair in Social Administration) – was carried out to ensure that junior staff did not lose their jobs. In the meantime, he had also been Deputy Dean and Dean of the Faculty of Social Sciences at Sheffield between 1982 and 1986. In retirement, he remained associated with the university as an emeritus professor; he also held visiting posts and served as president of the British Sociological Association from 1991 to 1993. He was also an Academician of the Academy of Social Sciences.