[6] 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.
[8][9] 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".
[12] Shortly after the death of his wife, Margaret, in 1933, Henry married his long-time friend and lover, fellow suffragist, Evelyn Sharp.