Ben Lightfoot studied at Peterhouse College, University of Cambridge, obtaining the BA degree with honours in geology in 1909. He won the Harkness prize for geology that same year and was later awarded the MA degree. He joined the British Geological Survey and, while stationed in Edinburgh, mapped parts of the island Mull and the Lanarkshire coal field. In 1911 he was appointed as a geologist of the recently formed Geological Survey of Southern Rhodesia (now Zimbabwe), directed by H.B. Maufe*, with headquarters in Bulawayo. With Maufe and A.E.V. Zeally* he started geological mapping in the Selukwe gold belt, in the centre of the country, but was soon sent to study the geology of the Wankie coalfield. His description of this work was published in the survey’s Bulletin 4 (1913). Thereafter he and Zeally mapped the Gatooma gold field. In 1914 Lightfoot studied the Karoo strata north of Bulawayo, but resigned in September that year to take up the Sorby Research Fellowship of the Royal Society, at the University of Sheffield, to conduct research on the Yorkshire coal field. However, these plans were disrupted by the start of World War I (1914-1918) and he joined the Topographic Section of the General Staff. From 1915 to 1918 he was in the Royal Engineers, reaching the rank of temporary major, and was awarded the Military Cross in 1915.
After the war Lightfoot spent some time in the employ of the firm Perrin and Marshall in Hyderabad, India, prospecting for coal, but returned to the Geological Survey of Southern Rhodesia in September 1921. Shortly thereafter he investigated the newly discovered Lydenburg platinum field in South Africa. In 1925 he found platinum mineralization at Makwiro, near Harare, and mapped the surrounding area. The next year he extended his survey to the extremities of the Great Dyke, thus conducting the first study of this unique geological feature. He then updated his survey of the Wankie coal field (Bulletin 15, 1929). In 1934 he succeeded Maufe as director of the Geological Survey. Most of his work was described in various publications of the Geological Survey, including the Annual Report of the Director, but other publications by him included a 'Note of an association of gold and tetradymite in Southern Rhodesia' (Transactions of the Geological Society of South Africa, 1927), 'Forty years of Rhodesian mining' (Rhodesian Mining Journal, 1930), 'An occurrence of gersdorffite in Southern Rhodesia' (Proceedings of the Rhodesia Scientific Association, 1931), and 'Rocks of southern Rhodesia and their minerals' (New Rhodesia, 1935).
In 1946 Lightfoot took early retirement and returned to Britain, where he worked as consulting geologist to the War Office for some years before finally retiring to Maidenhead, near London, and then to Hampshire.
Lightfoot became a member (later a Fellow) of the Geological Society of London in 1912 and was awarded its Lyell Fund in 1928. He became a member of the Geological Society of South Africa during his first stay in southern Africa, but his membership lapsed after he left the region. He joined the society again after his return and was elected vice-president from 1937 to 1942 and president in 1939. In 1942 he received the society’s Draper Medal. His presidential address dealt with the Great Dyke of Southern Rhodesia. In 1923 he became a member of the Rhodesia Scientific Association. He was also a member of the (British) Institution of Mining and Metallurgy, and in 1946 was made an officer of the Order of the British Empire (OBE). In 1921 he married Miss E. Longbottom, with whom he had two daughters.