J. Lyall Soutter, civil servant and amateur meteorologist, was the eldest son of John Soutter of Edinburgh and his wife Ann Lyall. He was educated at Stuart's College in that city. He came to the South African Republic (Transvaal) in 1888, settled in Pretoria, and on 9 January 1895, in Cape Town, married Rebecca J. Mitchell, with whom he had a son and two daughters. One of his interests was in sport. In 1892 he played football for Pretoria against Johannesburg and by 1908 was president of the Pretoria District Football Association.
From 1890 Soutter was employed by the government of the South African Republic in connection with surveying and town planning, though he was not admitted as a land surveyor. He laid out Pretoria West and named Soutter, Mitchell, Rebecca and Rose-Etta streets after members of his family. In the Staats-Almanak for 1898 (but not earlier) he was listed as a lithographic draughtsman on the staff of the surveyor-general. After Brittish forces took control of Pretoria in 1900 (during the Anglo-Boer War, 1899-1902) he was employed in the Field Intelligence Mapping Section, where he remained until the end of the war. In April 1902 he was appointed as a lithographer in the office of the surveyor-general of the newly created Transvaal Colony. After the formation of the Union of South Africa in 1910 he became principal clerk in the office of the surveyor-general of the Union, from April 1912. He resided in Arcadia, Pretoria.
Soutter's main interest outside his work was in meteorology. From 1891 onwards he measured the rainfall at the government buildings in Pretoria, keeping a complete record right through the Anglo-Boer War. His observations, in the form of monthly rainfall totals from 1891/2 to 1901/2, as well as mean air temperatures, were published in the first issue of the Transvaal Agricultural Journal in October 1902 under the title "Rainfall registered at Pretoria" (Vol. 1(1), pp. 53-56). Some further observations for September to November 1902, by Soutter and others, were published in the next issue of the same journal (January 1903, Vol. 1(2), pp. 55-56). When a Meteorological Department was created in the administration of the Transvaal Colony in 1903, headed by R.T.A. Innes*, Soutter and two other observers (T.N. Leslie* of Vereeniging and H.M. Guest* of Klerksdorp) immediately started supplying it with observations. Soutter continued his observations (of rainfall, air pressure, air temperature and humidity) until at least 1907.
In 1910 Soutter became a life member of the South African Association for the Advancement of Science. When the association held its annual meeting in Pretoria in 1915 he served as joint secretary of Section A, which included meteorology. He left Pretoria in 1913 to settle on the farm Kopje Alleen, some 30km east of Warmbad (now Bela Bela), where he continued his meteorological observations. In 1926 he published "Notes on rainfall at Kopje Alleen" in the South African Journal of Science (Vol. 23, pp. 172-178), with tables of monthly rainfall totals from 1913 to 1926. In a second paper, "Meteorological notes from Kopje Alleen" (Ibid, 1930, Vol. 27, pp. 126-131) he extended his results to 1930 and also provided some data on evaporation, air temperature and soil temperature for the period 1927-1930. By 1926 he had been elected a Fellow of the Royal Meteorological Society and was the secretary of the Nyl Basin Farmers' Association.