It is not known where or when he was born, but the birth date was probably in the late 1870s or early 1880s and in England. He died at Winterskoof, Natal, South Africa, on 2 December 1946.
His earliest association with forestry in that country was in the Orange River Colony, probably in the early l900s; the then Conservator recognized Robertson’s ability and was able to arrange for him to go to Yale University. He remained within the forest service of South Africa until he resigned in 1931. At the time of his retirement he was Chief Research Officer, Chief of Forest Management and Assistant Chief of Administrative matters to the Chief Conservator, which was the designation in those days of the Head of the Department of Forestry. The period 1913-31, when he was holding senior positions in the service was also a time when forestry was expanding rapidly, and Robertson was widely regarded by friends and opponents alike as a man who, by his ability, thoroughness, high ethical standards and prodigious capacity for work, contributed significantly to the development of forestry.
Robertson spent several months in Australia, making a careful study of the commercial timber species, especially the eucalypts, and the result was Forest Trees in Australia: a Reconnaissance (1925). The quality of his writings was evident in his student days at Yale, in his report on a visit to the pines of Mexico. The same high quality of work was still evident in his The Cultivation of Mexican Pines in the Union of South Africa (1931), which embodied all information then available.
He is honoured in the name Eucalyptus robertsonii Blakely (1927), and he was also collector of the type.