Primarily known as a Dipterist and Hymenopterist but 295 Coleoptera collected by him during the expedition to the River Amazon and the Cape Verde Islands on board the  S.S.'Faraday' 13 December 1895 - 14 April 1896 were acquired by the NHM in 1896 and 126 Coleoptera were among the insects from Sierra Leone the NHM acquired from him in 1899. There is an obituary by K.G. Blair in Ent.mon.Mag., 74, 1938, 42-43. (MD 6/18)

Educated at Wigan Grammar School and Oxford University, and made his career in the Civil Service (GCHQ). Moved to Cheltenham in December 1955, living at Benhill on the S.W. edge of the town in 1960-71 and then nearer the centre in Lansdown. He remained in Gloucestershire until 1988 when he retired to Embleton in Cumberland.

Published 'Deformed head of a fossil Plateumaris sericea L.' in Ent.mon.Mag.,108, 1972, 65. At the time of writing this he was attached to the University of Birmingham but moved subsequently to Faculty of Science, Department of Earth Sciences, University of Waterloo, Ontario, Canada. (MD 8/17)

Published 'Odontaeus armiger (Scop.) in Berkshire', in Ent.mon.Mag.,  97, 1961, 286. At this time his address was 86, Tachbrook Street, London, S.W.6. He has also published on Lepidoptera.  (MD 6/18)

Published detailed notes on the biology and ecology of Dolopius marginatus L. in Ent.mon.Mag., 81, 1945, 205-212, 274, and 62, 1946, 1-4. At that time he was attached to University College, Cathays Park, Cardiff. Also published on other groups in South Wales. By 1951 gave his address as Juniper Hall, Mickleham, Surrey. (MD 8/17)

The NHM purchased 864 beetles from various localities from Mrs Arnold in 1935. (MD 8/17)

76 coleoptera from various countries collected by himself and others together with other insects were part of the Imperial Bureau of Entomology gifts to the NHM in 1921, 1926 and 1935. (MD 8/17)

Naturalist, friend and companion of Thomas Wollaston on the voyage to Porto Santo and the Desertas. Wollaston dedicated Aleochara armitagei in homage to him and Cleonus armitagei for discovering the species. (Information from Mike Morris). (MD 8/17)

Collected beetles in the Gold Coast acquired by the NHM in July 1924. (MD 8/17)

Began his professional career as a clerk in the Customs Office at Liverpool when he collected, arranged and named all the specimens of the imports into Liverpool for the Great Exhibition of 1851. Subsequently took to lecturing in local institutions and educational establishments and became a Professor in the Liverpool Institution. In June 1860 he was appointed Superintendent of the Technological Museum in Edinburgh and from January 1866 Director. During his directorship he did much to shape the appearance of this institution now famous as the Royal Scottish Museum.