William Edward Watt, forester, was the son of the medical practitioner Dr William John Watt. He received his secondary schooling at Maritzburg College, a boys' high school in Pietermaritzburg, and passed the matriculation examination of the University of the Cape of Good Hope at the end of 1908. The next year he continued his studies at the Natal University College, which was in the process of being established at that time, and at the end of 1911 passed the Bachelor of Arts (BA) examinations of the University of the Cape of Good Hope with honours in botany. In 1912 he was awarded the Natal Rhodes Scholarship and proceeded to the University of Oxford to study forestry, obtaining the Forestry Diploma in 1914. While still in the United Kingdom World War I (1914-1918) broke out and he immediately reported for military duty. He was posted to King Edward's Horse as a corporal, then as a second lieutenant, but later joined the Royal Flying Corps as an observer and pilot until the end of the war, with the rank of lieutenant. He was awarded the Air Force Cross for his outstanding service in 1922.
Upon his return to South Africa Watt was appointed as assistant district forest officer under Dr J. D. M. Keet in the Department of Forestry, with his headquarters at Knysna, assuming duty in September 1919. Most of his field work was done in the Midland Conservancy where, among others, he compiled an enumeration of the indigenous forests. In 1929 he moved to the Head Office of the department in Pretoria, where he remained for the rest of his career. He served as assistant to the Director of Forestry, then as Assistant Director of Forestry, and finally as Director of Forestry from December 1944 to his retirement in May 1951. During this entire period he did not publish much research. In 1935 he delivered a paper on "Forest protection from fire in South Africa" at the Fourth British Empire Forestry Conference held in South Africa. In 1947 he published a paper on "The conservation of existing forests and the need to plant forest trees for effective soil conservation in the Union of South Africa" in the South African Forestry Journal. He was, however, one of the prime movers in establishing the South African Forestry Association in 1938 and actively participated in its activities for many years. During 1938-1939 he served as the association's first secretary-treasurer and, except during 1955-1957, was a member of the executive committee from its inception in 1938 to 1968 when ill health intervened. During this long period he served as the committee's chairman (1951-1954), vice-chairman (1958) and secretary-treasurer (1938-1939, 1960-1968). His minutes of the annual meetings of the association and the annual reports of its executive committee were regularly published in the South African Forestry Journal.
After his retirement Watt became a forestry consultant to the Rand Mines Group. He resigned from this position in 1957 to practice as a private forestry consultant for some years. He was married to Margaret Amy Fisher, with whom he had four sons.
