He was hired by Harper's Monthly Magazine to investigate rumours of a trade in slaves from Angola to the cocoa plantations of São Tomé. After a 450-mile journey inland, he uncovered a trail of people being handed over to settle debts or seized by Portuguese agents and taken in shackles to the coastal towns. Once there he was enraged to find that Portuguese officials "freed" them and changed their status to that of voluntary workers who agreed to go to São Tomé for five years. Despite ill health so severe that he feared he had been poisoned Nevinson followed the slaves' journey to São Tomé. He found conditions on the plantations so harsh that one in five workers died each year. His account was serialised in the magazine from August 1905 and published as "A Modern Slavery" by Harper and Bros in 1906.
Reviewing Nevinson's book, More Changes, More Chances (1925), E. M. Forster described the book as "exciting", and noting that Nevinson had joined the British Labour Party, stated: "He has brought to the soil of his adoption something that transcends party - generosity, recklessness, a belief in conscience joined to a mistrust of principles".[10]
He married Margaret Wynne Jones; and their son was the artist Christopher Nevinson. During their marriage he had a long term affair with Nannie Dryhurst which ended in 1912.[12] Shortly after the death of his wife, Margaret, in 1933, Henry married his long-time friend and lover, fellow suffragist, Evelyn Sharp. He died in 1941, aged 85.
Between the Acts: Autobiographical and other sketches. (1904)
Sketches on the Old Road through France to Florence. By A. H. Hallam Murray, accompanied by H. W. Nevinson and Montgomery Carmichael. (Pt. 1 [France] by H. W. Nevinson. Pt. 2 [Italy] by M. Carmichael.) (1904)
^ abcde"Nevinson, Henry Woodd" by H. N. Brailsford, revised by Sinead Agnew. Oxford Dictionary Of National Biography : From the Earliest Times to the year 2000. Editors, H.C.G. Matthew and Brian Harrison. Oxford University Press, 2004. ISBN019861411X (Volume 40, pp. 551-2).
^See Nevinson's Fire of Life pp.304–318 for his time at the Dardanelles; he doesn't mention his own wound.
^Men's Political Union for Women's Enfranchisement (1911). First Annual Report (Report). London: Women's Printing Society.
^Men's Political Union for Women's Enfranchisement (1912). Second Annual Report (Report). London: Women's Printing Society.
^Men's Political Union for Women's Enfranchisement (1913). Third Annual Report (Report). London: Women's Printing Society.
^E. M. Forster, "Literature or Life?" The New Leader, 2 October 1925. Reprinted in P. N. Furbank (ed.), The Prince's Tale and Other Uncollected Writings. London: Andre Deutsch, 1998. ISBN0233991689 (pp. 89-93)