Filmer spent his early life in Western Australia and won a Government Exhibition Scholarship which took him to the University of Melbourne from which he graduated B.V.Sc.
During his period in Western Australia, Filmer, in collaboration with E. J. Underwood, achieved a major research success which was to prove of incalculable benefit to agriculture in New Zealand and throughout the world.
Filmer and Underwood showed that the beneficial effect of iron compounds resided in the minute amount of cobalt present as an impurity.
He emigrated to New Zealand in 1938 where he soon became director of the Animal Research Division of the Department of Agriculture, a position he held until his retirement in September 1960.
In 1968, Massey University conferred on Filmer the degree of Honorary Doctor of Science and in 1971 he was elected a Life Fellow of the Australian College of Veterinary Scientists.