He is currently a member of the Standing Committee of the Association of Heads of Independent Schools of Australia, the Western Australian Anglican Schools Association, a Trustee of the International Boys' Schools Coalition, a member of the sub-committees of Anglicare WA (Strategic Planning) and the Association of Independent Schools (WA) (Education).

Prior to his appointment at Christ Church, Garth had a varied career in education working as a Boarding Housemaster and in a range of roles primarily concerned with the administration of Pastoral Care in independent schools in Australia (Queensland, New South Wales and Western Australia) and the United Kingdom (Tonbridge School, England). His particular co-curricular interest is Cricket and he has coached and coordinated the sport in all of the schools in which he has worked.

He is married with three children: Emma, Amy and Lachie.