Captain Gilbert first joined the 48th Highlanders at the age of 16 as part of the Unit`s 1964 Student Militia Course and was later an instructor in that Program. He served actively, throughout the 1960s and 70s, both in the Regiment, in various Platoon, Company and Battalion level appointments, and as a Staff Officer, in both the Administrative and Operations Branches, at Toronto Militia District Headquarters. During these years, he participated in the Unit`s 1967 Trooping of its Colors, as part of Canada`s Centennial celebrations, and was also a section commander in the unit’s Mobile Command (MOBCOM) Reserve Company. In 1972 and 1974, he deployed on two major Arctic Sovereignty Exercises. In 1980, he transferred to the Supplementary Reserve, in order to pursue his civilian career. He returned to the Regiment in 1990 and served as unit Adjutant during and after the Regiments 100th Anniversary year in 1991. Subsequently, he transferred to the local formation headquarters, at 32 Canadian Brigade Group, where he served as a part time and eventually full time staff officer in Public Affairs and various other appointments, including that of Headquarters Adjutant, until his retirement in 2008.

He came out of retirement to join the Cadet Instructor Cadre and serves, in that capacity, as a member of the St Andrew`s College Cadet Corps, a unit which has strong affiliations with the 48th Highlanders of Canada. In addition to his work with the 15th Battalion Project, Captain Gilbert has been, since 2006, the Editor of the Regimental Journal, The Falcon.

In his civilian life, Captain Gilbert was, for thirty years, a high school teacher, teaching History and Co-operative Education at Weston Collegiate Institute in Toronto. He currently teaches in the Faculty of Continuing and Professional Studies at Sheridan College.