Ethel Sheila Coates was born in Carbon, Alberta to John Hubert Coates (an immigrant homesteader from London, England) and Edith Coates (Tirney) on January 16, 1922. She grew up on her parents’ farm, but spent most of her school years in Toronto (where her mother was from) and completed high school in Alberta. Her niece suggests that she may have had some formal training as a secretary, and an Ethel Sheila Coates is listed as having passed the Canadian federal government’s stenographers’ civil service exams in May 1941.
She left the family farm and moved to the Northwest Territories alone and worked for Imperial Oil in Normal Wells for a number of years in the 1940s. It appears that she was one of the few secretaries or female employees living and working in Norman Wells, and that she chose to remain there after the wartime project (the Canol project) was completed. According to her niece, she loved the Northwest Territories and referred to her time there as the best time of her life.
Later she moved to Devon, Alberta, where she lived and continued to work for Imperial Oil for approximately thirty years in total. In Alberta, she worked at the Leduc gas plant, which opened in 1950, and taught skiing at the local Devon ski hill. She traveled extensively internationally in the 1950s and 1960s. She did not marry.
She identified as an environmentalist, and established the Coates Conservation Lands as a bequest to the Edmonton Area Land Trust. She died in August 2014 in Devon, Alberta.