William C. Slim was born in Vancouver, B.C. He joined the Royal Canadian Air Force Cadets at the age of 14. At age 16 he signed onto the Royal Canadian Air Force Auxiliary until high school graduation then transferred to the Regular Force.
After initial training in electronics and airframe mechanics he served at postings in Montreal, Quebec, and Cold Lake, Alberta.
In 1976 he became active aircrew serving with a tactical helicopter squadron flying Twin Huey helicopters.
This was followed by a posting to Ottawa where flying duties involved the transport of Federal Cabinet Ministers about North America.
After promotion he was transferred to Greenwood, Nova Scotia, for a tour on the Aurora Maritime Patrol Aircraft as a Flight Engineer.
In 1988 he resigned from the Forces after 26 years of service. Following a move to Victoria and schooling at the University of Victoria he spent 3 years employed at HMC Dockyard finishing his public service career as CFB Esquimalt Web Master.