He wrote a long poem published in two parts called "The Wrongs of Africa" (1787–1788), and entered into a controversy with an ex-Roman Catholic priest called Fr Raymond Harris, who tried to justify the slave trade through the Bible (and was generously paid for his efforts by Liverpool businessmen involved with the slave trade). Roscoe also wrote a pamphlet in 1788 entitled 'A General View of the African Slave Trade'. Roscoe was also a political pamphleteer, and like many other Liberals of the day hailed the promise of liberty in the French Revolution.