Son of businessman Thomas Callender Campbell, Howard was born in Derry, the oldest of nine siblings, and took an interest in the local moths and butterflies from an early age.
A Foyle College magazine had a picture of him under the heading "The Bringing of the First Football Cup to Derry."
He played tennis and cricket in India, organizing village matches and rallying people for various causes including, on one occasion to fix a reservoir on the verge of breaching.
In 1909 he was appointed head of the United Theological College at Bangalore but he did not take it up due to an illness which was diagnosed as sprue.
[7] He also collected insect specimens mainly from southern India, some of which he sent to Walter Rothschild and are now held in the Natural History Museum, London.
Some of the species described (but may not currently be considered valid) from his collections include Phthonoloba auxostira, and Abraxas prosthetocneca, Homoptera ruficolora, Bleptina heteropalpia, Rhynchina leucogonia, Hypena mesogramma, H. molybdota, Mecistoptera albisigna, Cidaria nyctichroa, Chilo araealis, Phycita umbratalis, Stemmatophora aedalis (now considered a synonym of Hypsopygia fuscalis), Oligostigma chrysozonalis, Nacoleia pachytornalis, Nacoleia megaspilalis, and Calamochrous bipunctalis.
He wrote several Telugu books including (translated titles) Grounds for Belief in a Personal God (1893), Christian Evidences (1898), Christian Theology (1905) and along with Veerasalingam Pantalu helped revise Browne's Telugu-English Dictionary (1906) and Arden's Telugu Grammar (1908).