Born in Colac, Victoria, and an enthusiastic fan of science fiction, Harding was among the founding members of the Melbourne Science Fiction Club. Other members of the club were: Race Mathews, Bertram Chandler, Bob McCubbin, Merv Binns and Dick Jenssen.
In 1961, Harding's short story, Displaced Person, was published in Science Fantasy. He continues to write and submit stories to a range of magazines, including New Worlds, Science Fantasy and Science Fiction Adventures. In 1966, John Bangsund started the Australian SF Review (ASFR) and Harding and John Foyster became partners in producing this fanzine publication. This publication closed in 1969 and Harding went on to write for SF magazine, Vision of Tomorrow set up by Ron Graham.
From 1978 Harding switched from photography to writing full time. Harding has also written short stories using the pseudonym, Harold G Nye.