Harry Gordon Johnson was born on 26 May 1923 at Victoria Memorial Hospital in Toronto. He was the first child of Henry Herbert Gordon Johnson, who was also known as Harry, and Frances Lily Muat. Harry senior had been born in 1891, one of six children of a master plumber who had come to Canada from southern Ireland. Frances Muat's father had come from Scotland at age 19, served in the Governor General's Guards in the North-West Rebellion, and eventually spent twenty-six years as a travelling salesman for H. J. Heinz. He became president and secretary of the Canadian Grocers Association. Frances had two sisters. Harry senior was educated at Jarvis and Riverdale Collegiate Institutes in Toronto and entered the University of Toronto in 1910 as a student of engineering. He did not go past his second year. Frances, who had been educated at Jarvis Collegiate and Westminster College also entered the University of Toronto in 1910 as a student at University College. She graduated in 1914 and proceeded to the University's Faculty of Education as a general student in 1914–15 before beginning her teaching career at Souris, Manitoba, where she taught English, history, and modern languages. After a year, however, she returned to Toronto to marry Harry senior, who had become a journalist, initially with the Toronto World, then with the Mail and Empire and the Globe, where he rose to be city editor.