George Watson Robertson qualified as a member of the Royal College of Surgeons (MRCS) of England, and a licentiate of the Royal College of Physicians (LRCP) of London, in 1893. He came to the Cape Colony in 1897 and during the rinderpest epizootic that year temporarily assisted Dr A. Edington* of the Government Bacteriological Laboratory, Grahamstown, on rinderpest duty. He was licensed to practice medicine in the Cape Colony on 4 may 1898. In October 1897 he was appointed as assistant government bacteriologist (from 1899 medical assistant) under Edington at Grahamstown, and when the latter was on sick leave for six months during 1901 continued with the laboratory's research programme. That year he was transferred to Cape Town on special duty as plague medical officer and bacteriologist. From April 1902 he served as bacteriological assistant to the Local Government and Health Branch of the Colonial Secretary's Department. Some time after the formation of the Union of South Africa, in April 1912, he was appointed government bacteriologist in charge of the Public Health Laboratory, Cape Town. From 1907 he furthermore acted as medical officer in charge of the government vaccine and lymph station at Rosebank, Cape Town. Later he also acted as government pathologist in charge of the Cape Town morgue, and was a member of the Robben Island Leprosy Committee. In 1916 he was co-author with Dr James A. Mitchell* of "A note on the transmission and examination of plague specimens", that was published in the South African Medical Record (Vol. 14, pp. 71-72). He remained at the Government Laboratory, Cape Town, until his retirement in 1936.
Robertson became a member of the South African Philosophical Society in 1905 and when it became the Royal Society of South Africa in 1908 was elected one of its first Fellows. He served on the society's council in 1919. In 1905 he also became a member of the British Association for the Advancement of Science in 1905.
George Watson Robertson should not be confused with some other medical practitioners who had similar names and practiced in the Cape Colony at the same time:
Dr George Whiteside Robertson (or George Henry Whiteside Robertson) qualified in Edinburgh as Bachelor of Medicine (MB) and Master of Surgery (CM) in 1898, was licensed to practice in the Cape Colony on 24 October 1899 and resided at Cathcart until at least 1907. In 1911 he was awarded the bronze medal of the Order of the Hospital of St John of Jerusalem in England, for conspicuous heroism.
Dr George Dunlop Robertson qualified as a Licentiate of the Royal College of Physicians and of the Royal College of Surgeons of Edinburgh in 1893, was licensed to practice in the Cape Colony on 26 September 1895, served as district surgeon at uMzimkhulu, Transkei, but by 1907 resided at Southampton, England.
Dr George Officer Robertson qualified in Aberdeen as Bachelor of Medicine (MB) and Bachelor of Surgery (ChB) in 1902, was licensed to practice in the Cape Colony on 6 November 1905, and resided first at Hopetown and later at Belfast in the Transvaal.