Kenneth Marsden Johnston (1922–1987) was born in Toronto on 4 January 1922 to Kenneth Irwin McKenzie Johnston (1879–1930) and Clara Augusta Leeker (1888–1970). In Toronto, the Johnstons lived at 47 Oriole Parkway and ran the Johnston Lumber Company Limited, which had been established in 1910. Kenneth Marsden graduated from St Andrew's College (Aurora) in 1941. During the war, Johnston served as an officer in the RCNVR and was aboard HMCS Bellechasse. He joined Wood Gundy & Company sometime in the 1940s in Toronto. In 1950 he moved to their Edmonton office, and in July 1951 set up and became manager of a new office in Calgary. In the late '50s and early '60s he was a director of Husky Oil. He retired at the end of 1963.

On 21 September 1946, Johnston married Margaret Lillian Ballentine (1923–1983) at the Bishop Strachan School chapel in Toronto. They had three children: Lynn, Pamela, and Robert. He died on 25 November 1987 in Toronto.