Horace Sydney Kendall Simpson passed the matriculation examination of the University of the Cape of Good Hope in 1900, during the Anglo-Boer War (1899-1902). In 1905 he passed the university's Survey Certificate Examination and soon thereafter was admitted as a land surveyor in Natal Colony. A few years later he published a textbook on Practical land surveying: Notes compiled for survey students in South Africa (Cape Town, 1908, 174p). He spent a large part of his subsequent career in Dundee, KwaZulu-Natal. His life was mostly dedicated to furthering the profession of land surveyor and he led an active public life which culminated in his nomination as a senator. He was one of the foundation members of the Institute of Land Surveyors of Natal in 1905, was elected as vice-president of the Institute for the year 1923/4, served as a member of council to 1926, and again as vice-president for 1926/7.
In the mid-1930's Simpson assisted H.E. Maasdorp in measuring the Kaitob baseline as part of the geodetic work of the Trigonometrical Survey. They used the British Ordnance Survey 'Macca' apparatus and invar tapes suspended in catenary arcs. Simpson and J.H. Steere also measured the Mtubatuba baseline. This was the last baseline measured with tapes before the advent of electromagnetic distance measurement. Simpson described the work in 'Report on Mtubatuba base measurements' (South African Survey Journal, 1938, Vol. 5(35), pp. 51-58 and 1939, Vol. 5(37), pp. 147-149).
Simpson practised also as an architect. He was a member of the South African Institute of Architects (from which he resigned around 1930) and among others designed the Public Hall, Dundee, in 1922.
Simpson and his wife, Emilie Antionette Josephine Simpson, whom he married in Durban in 1912, were the parents of the surveyor Kendall Wynne Simpson and the geologist Eric Stanley Wynne Simpson.