Harry Leighton Hare, son of William Hare and his wife Francis, born Hooper, joined the civil service of the Cape Colony on 9 February 1902. During the next ten years or so he worked as a clerk in Tulbach and Cape Town. After the formation of the Union of South Africa (in 1910) he was employed in the Department of Justice as a third grade clerk attached to the magistrate court in Philipstown, Cape Province. In 1916 he became a foundation member of the South African Biological Society. In the society's lists of members for 1919 and 1920 his address is given as Zwagershoek, a farm some 10 km south of Philipstown.
Hare published several ornithological papers and notes over a period of more than three decades. His first paper described "The birds of Philipstown, Cape Province, with notes on their habits" (Journal of the South African Ornithologists' Union, 1915, Vol. 11(1), pp. 1-19). This was followed many years later by several contributions to the journal Ostrich: "Vultures, crows and sheep" (1932), in which he described the return of vultures to the Philipstown district after an absence of 40 years; "Records of unusual habits of birds" (1932); "Remarks on changed conditions in the Karroo in recent years" (1937), describing the effects of drought and overstocking; and, as co-author with J.M. Winterbottom, "On the birds of Port St Johns, Pondoland" (1947).