Hamilton, Gerard Edwin Hamilton Barrett- (1871–1913), zoologist, was born in India of an Irish father, Capt. Samuel Barrett of Dublin, and Laura Barrett (née Thomson) of York, England. The family returned to Ireland to live at Kilmanock, Co. Wexford, when he was aged three years. He was educated at Trinity College, Cambridge, where he graduated BA and formed a strong friendship with Edward Adrian Wilson, the naturalist and artist who accompanied Capt. Robert Falcon Scott and Sir Ernest Shackleton (qv) during the 1901–4 Discovery expedition to Antarctica to their then ‘furthest south’, and who later reached the South Pole before he perished on the return journey with Scott in January 1912.
Barrett-Hamilton was an acknowledged expert on British mammals and author of the first fifteen parts of History of British mammals, before the series was halted by his untimely death; M. C. Hinton of the British Museum was engaged to complete the work. Wilson had illustrated fourteen parts when his death occurred. The fourteenth part, when published, included an obituary notice on the gifted artist in which Barrett-Hamilton noted that both men ‘had at Cambridge attended the same lectures, frequented the same laboratories, and finished equal in the tripos of 1894. Both were candidates to the scientific staff of Scott's first Antarctic expedition (1901–4), for which one alone could be appointed. To the rejected applicant fell the consolation of compiling for the use of his successful rival the chapter on seals in the Antarctic manual (1901)’ (Report of the natural history collections of the Southern Cross mammalia).
He contributed to Cybele Hibernica, and his work is listed in the index of authors. He also contributed a study of mammals to the Clare Island survey (‘The mammalia of Clare Island’, part 17 of the survey, RIA Proc., xxxi (1912)). His papers on the Irish black rat (Zoology, 1891) and Irish stoat (Zoology, 1895), according to his obituarist C. B. Moffat, ‘possess an interest and authority that cannot be ignored’. He was elected FZS and MRIA. On behalf of the colonial office and the British Natural History Museum he went to South Georgia to conduct an investigation into the indiscriminate slaughter of whales in the seas around the Falkland Islands. He died from pneumonia on South Georgia on 17 June 1913. His remains were brought home and buried in the churchyard of Duncannon, Co. Wexford, on 2 March 1914.