William Henry Newdigate was a son of Francis Newdigate and his wife Lady Barbara Maria, born Legge, daughter of the third Earl of Dartmouth. He came to South Africa in 1847 and bought farms in the Plettenberg Bay area which he named "Buccleugh" and "Redbourne". In 1851 he was appointed justice of the peace at Plettenberg Bay. In June that same year he married Caroline Duthie, with whom he had three sons and six daughters. Their eldest daughter, Caroline B. Newdigate* collected natural history specimens.
William bought a large estate in the Tsitsikama Forest and in 1863 built a mansion on it which he named "Forest Hall". In 1867 he requested the colonial government to supply him with seeds or plants of "China grass" (Boehmeria nivea, a fiber plant), and three years later asked that a weekly mail service be established between Forest Hall and Plettenberg Bay. Various documents relating to the Newdigate family are housed in the National Library of South Africa, Cape Town.
In 1878 William donated moths from the Plettenberg Bay area to the South African Museum. Later Roland Trimen* acknowledged "the late Mr W.H. Newdigate" in the preface of his South African butterflies... (1887-1889) for contributing a small series of butterflies from Knysna.