Bill Sarjeant received his BSc and PhD in Sheffield and his DSc in Nottingham, England. In 1972 he and his wife Margaret moved to Saskatoon, where he joined the Department of Geology. Sarjeant was a voracious reader, folksinger and harmonica player, collector, naturalist, author of historical fantasies and of more than fifty articles on Sherlock Holmes, as well as an influential member of the Saskatoon and Saskatchewan heritage communities.
First and foremost he was a geologist and paleontologist who wrote the ten-volume bibliography, Geologists and the History of Geology, and had the world's largest private collection on the history of geology - part of an 85,000-volume personal library. He co-authored The Tracks of Triassic Vertebrates: Fossil Evidence from North-West England, a coffee table book on fossil traces of dinosaur footprints, and wrote over 350 articles on geology topics. He was a member of the International Jurassic Sub-Commission of the International Union of Geological Sciences. He received the 1990 Sue Tyler Friedman Medal, given by the Geological Society of London, and the 1991 Founder's Medal of the Society for the History of Natural History of London. In 1998 he was elected a Fellow of the Royal Society of Canada.
At various times Sarjeant was chairman of the Special Committee on the Identification of Historic Buildings for Saskatoon City Council, a member of the Saskatchewan Heritage Advisory Board, a director of Saskatchewan Culture, president of the Saskatoon Environmental Society, and a member of the Preservation Committee of the Society for the Study of Architecture in Canada. He was also an executive member of the Saskatoon branch of the Community Planning Association of Canada, a member of the Saskatchewan Archives Board, and chairman of the Saskatchewan History Advisory Board.
He co-authored Saskatoon's Historic Buildings and Sites (1973) with Sally Club, as well as a version of Bill Delainey's MA thesis: “Saskatoon: The Growth of a City” (1974). With John Duerkop he wrote the official souvenir of Century Saskatoon, called Saskatoon: A Century in Pictures (1982). He edited the annual Saskatoon History Review for sixteen years. He was a major force behind drafting the Saskatchewan Heritage Act, led the fights to save the CPR Station and the Capitol Theatre in Saskatoon, and helped create the Municipal Heritage Advisory Committee Award. Amongst the awards he received were a 1977 provincial award for contributions to the heritage community, a Century Saskatoon Medal in 1982, and Saskatoon City Council's 1990 Volunteer Heritage Public Service Award.