Ernest William Lannin came to South Africa from Ireland around 1892 to work as a surveyor for the Simmer & Jack Gold Mining Company in Johannesburg. In 1900 he moved to Southern Rhodesia (now Zimbabwe) where he worked on a number of mines, including Kimberley Reef at Bindura (1909), the Alaska Copper Mine at Chinhoyi (1917), Tin Hat at Hope Fountain, near Bulawayo (1922), and Christmas Pass Mine at Mutare (from 1923). He furthermore owned the Marconi and Oscola Mines at Mazowe, just north of Harare. He was married to Verna M. Buchanan, and they had two daughters.
Lannin was keenly interested in butterflies and devised a bait trap to catch specimens of the genus Charaxes - high-flying, stout-bodied, tropical Brush-footed butterflies (family Nymphalidae) - often using fresh dog droppings as bait. He was furthermore the initiator in Zimbabwe of butterfly transfers, the delicate process of transferring the wing-scales to a waxed or gummed card. As a skilled photographer his speciality was the colouring of black and white photos at a time long before colour film became available.
Some of his specimens were collected on weekend excursions across the border into Mozambique (then Portuguese East Africa) when he resided at Mutare. In 1924 he published a paper, "Charaxes of Rhodesia and Portuguese East Africa" in the South African Journal of Natural History (Vol. 4(5), pp. 308-316). Unfortunately his collection of lepidoptera and albums of transfers were dispersed after his death, but some of the material went to the National Museum of Zimbabwe. A Hawk moth, Nephele lannini was named after him by Dr H.E.K. Jordan.