William T. Hallimond, civil and mining engineer, was a son of the engineer John H. Hallimond and his wife Jane H.B. Hallimond, born Escombe. He was educated at Cleveland College, Darlington, in the county of Durham, served an apprenticeship at the collieries of Etherley and Newton Co., and in 1877 became manager of Durham Main Colliery, near the city of Durham. He came to South Africa in November 1881 as manager of the Great Stormberg Coal Co., Ltd., where he remained to the end of 1882. He was then appointed by the railway contractors Pauling and Co. as engineer and contractor's agent on the construction of the railway line to Aliwal North. From 1888 to 1899 he worked as manager or consulting engineer at the Cyphergat Coal Co., Botha's Reef Gold Mining Co., Rand Collieries, Cape Collieries, and other companies. During this period, in August 1893, he applied unsuccessfully for an appointment as mining engineer or mining inspector in the South African Republic (Transvaal). From 1899 to 1904 he was surveyor at Jumpers Deep, Ltd. on the Witwatersrand, but during the Anglo-Boer War (1899-1902) acted as correspondent for The Times with the British forces. Later in the war he was employed by Field Intelligence, returning to Johannesburg in April 1901. From 1904 he was mine manager and mining engineer at Crown Deep, Ltd., Johannesburg, for several years, but later worked for Cleopatra Gold Estates in Barberton.
Hallimond was a member of the (British) Institute of Mining and Mechanical Engineers. In January 1898 he joined the South African Association of Engineers and Architects, and in 1903 the South African Association for the Advancement of Science. He became a member of the Chemical, Metallurgical and Mining Society of South Africa in 1904 and served on its council for 1905/6. He published the following papers: "Notes on the coal seams of the Transvaal and description of a modern pit-head plant" (Transactions of the Institute of Mining Engineers, Newcastle, 1897); "Mica in the Transvaal" (Mining Magazine, London, 1906); and "The Olifants River mica belt" (1915) and "Prospects of the Ophir Gold Mines" (1916), both in the South African Mining Journal.
At his death in 1923 Hallimond was survived by his wife, Sarah Louisa Hallimond, born Norland, and four children.