Ignatius Sancho was born on a slave ship in 1729; his precise birthplace is thus unknown. After his mother died in the Spanish colony of New Granada and his father committed suicide rather than live as a slave, Sancho was taken to England and in 1731 was given to three maiden sisters living in Greenwich. While a young man, he met John Montagu, 2nd Duke of Montagu, who took an interest in his education (much as Montagu already had in Francis Williams's education), and in 1749 Sancho ran away and sought refuge with the Montagu families. The Duke had just died but his wife agreed to employ him as butler; when the Duchess of Montagu died in 1751 she left Sancho an annuity of £30 and a year's salary. The salary and his savings gave Sancho £70 in available money, which he spent on women, gambling, and the theatre. An attempt at a career as an actor, playing roles in Othello and Oroonoko, failed.

In 1766, Sancho became valet to the newly recreated George Montagu, first duke of the new creation and son-in-law of his earlier patrons. In 1768, Sancho's portrait was painted by Thomas Gainsborough. With help from Montagu, Sancho and his wife, Ann Osborne, set up a grocery shop in Westminster, early in 1774. In addition to shopwork, Sancho wrote and published a Theory of Music and two plays. As a financially independent male householder living in Westminster, Sancho qualified to vote in the parliamentary elections of 1774 and 1780; he was the first black person of African origin known to have voted in Britain. At this time he also wrote letters and in newspapers, under his own name and under the pseudonym "Africanus": he supported the monarchy and British forces in the American Revolutionary War.

Ignatius Sancho died from the effects of gout on December 14, 1780, and became the first African to be given an obituary in the British press. Two years later, Frances Crewe arranged for his letters to be published; these appeared as the two-volume The Letters of the Late Ignatius Sancho, an African. The book sold very well, and his widow received over £500 in royalties.

A plaque to the memory of Sancho was unveiled on June 15, 2007, by Nick Raynsford, MP for Greenwich, on the remaining wall of Montague House on the south west boundary of Greenwich Park. The plaque was funded by Friends of Greenwich Park to commemorate bicentenary of the Abolition of the Slave Trade Act, made law in 1807.

Friends of Greenwich Park newsletter. Summer 2007.