Allen initially worked in Rhodesia before coming to Australia. He became Curator of the Botanical Gardens for Darwin, N.T., on 7 October 1913 and finally retired from the public service on 21 February 1936 . He served with the Australian Expeditionary Force 1915-19. On his return to the N.T. in 1919 he was placed in charge of the new Department of Agriculture, with the title of Superintendent of Agriculture (later reclassified as Inspector of Agriculture) and Curator, Botanic Gardens . Added to this in April 1920 was that of Inspector under the Plant Diseases Ordinance. His emoluments included free quarters and the house in which he lived is still standing and has been taken over by the local Historical Society.Allen was interested in the collection of plants, especially any which could be of economic import-ance. Most specimens were sent to J. H. Maiden, Sydney, for identification, but some were sent to the Royal Botanic Gardens, Kew, England. In his promotion of agriculture and the development of the Botanic Gardens, Darwin, he corresponded with a number of Departments of Agriculture and Botanic Gardens overseas and in 1914 attended an International Exhibition in Java, as well as studying methods of agriculture in that country.
Source: Hall, N. (1978) Botanists of the Eucalypts. CSIRO, Melbourne.