Granville Sharp, the ninth and youngest son of Thomas Sharp (1693–1758) and his wife, Judith Wheler,was born in Durham on 10th November 1735. The son of the archdeacon of Northumberland, and the grandson of John Sharp, the Archbishop of York, he decided against a career in the Church of England and instead served an apprenticeship in May 1750 to a Quaker linen draper in London.
According to his biographer, Grayson Ditchfield: "These contacts encouraged Sharp to engage in theological disputation, and he used his leisure to acquire that largely self-taught knowledge of Greek and Hebrew which formed an important basis for his career as a writer."
In 1757 he completed his apprenticeship and became a freeman of the City of London as a member of the Fishmongers' Company. The following year he obtained a post as a clerk in the Ordnance Office at the Tower of London. In 1764 he received promotion to the minuting branch as a clerk-in-ordinary.
In 1765 Sharp was living with his brother, a surgeon in Wapping. One day Jonathan Strong, a black man, arrived at the house. Strong was a slave who had been so badly beaten by his master, David Lisle, that he was close to death. Sharp took Strong to St. Bartholomew's Hospital, where he had to spend four months recovering from his injuries. Strong told Sharp how Lisle, had brought him to England from Barbados. Lisle had apparently been dissatisfied with Strong's services and after beating him with his pistol, had thrown him onto the streets.
After Jonathan Strong had regained his health, David Lisle paid two men to recapture him. When Sharp heard the news he took Lisle to court claiming that as Strong was in England he was no longer a slave. However, it was not until 1768 that the courts ruled in Strong's favour. The case received national publicity and Sharp was able to use this in his campaign against slavery.
Hugh Thomas, the author of The Slave Trade (1997) has pointed out: "Sharp put this matter further to the test in the case of the slave Thomas Lewis, who, belonging to a West Indian planter, escaped in Chelsea. When he was recaptured, and shipped to begin the journey to Jamaica, Sharp served the captain on his boat with a writ of habeas corpus. The case came before Lord Chief Justice Mansfield, who put to the jury the question whether the master had established his claim to the slave as his property. If they decided affirmatively, he would rule whether such a property could persist in England. The jury decided that the master had not established his claim. So the main question was left unsettled. Lord Mansfield said, rather curiously, that he hoped that the question whether slaves could be forcibly shipped back to the plantations would never be discussed."
In 1769 Sharp published A Representation of the Injustice and Dangerous Tendency of Tolerating Slavery. Soon afterwards he began to correspond and collaborate with the Quaker abolitionist Anthony Benezet and the Philadelphia abolitionist Benjamin Rush. He also took up the cases of other slaves such as James Somersett, and convinced the courts that "as soon as any slave sets foot upon English territory, he becomes free."
Granville Sharp developed radical political opinions about other issues as well. He argued in favour of parliamentary reform and an increase in the low wages paid to farm labourers. Sharp also supported the American colonists against the British government and as a result, had to resign from the civil service in 1776.
In April 1780 John Cartwright helped establish the Society for Constitutional Information. Granville Sharp joined the organisation. Other members included John Horne Tooke, John Thelwall, Granville Sharp, Josiah Wedgwood, Joseph Gales and William Smith. It was an organisation of social reformers, many of whom were drawn from the rational dissenting community, dedicated to publishing political tracts aimed at educating fellow citizens on their lost ancient liberties. It promoted the work of Tom Paine and other campaigners for parliamentary reform. Sharp's biographer, Grayson Ditchfield, has pointed out that "Sharp corresponded with Christopher Wyvill, John Jebb, and other reformers; he wrote strongly against triennial parliaments as an insufficient measure; and he supported the legislative independence of the Irish parliament. In the belief that the ancient constitution represented people rather than property, and as an alternative to the universal suffrage for which he was not an enthusiast, Sharp advocated a revival of the Anglo-Saxon system of frankpledge. It would involve a system of administration from tithing courts to parliament, which would secure the involvement in government, and the preservation of the rights, of an active citizenry."

Granville Sharp
In June 1786 Thomas Clarkson published Essay on the Slavery and Commerce of the Human Species, Particularly the African. As Ellen Gibson Wilson has pointed out: "A substantial book (256 pages), it traced the history of slavery to its decline in Europe and arrival in Africa, made a powerful indictment of the slave system as it operated in the West Indian colonies and attacked the slave trade supporting it. In reading it, one is struck by its raw emotion as much as by its strong reasoning." William Smith argued that the book was a turning-point for the slave trade abolition movement and made the case "unanswerably, and I should have thought, irresistibly".
During this period Sharp became interested in another issue. In 1786 Jonas Hanway established the Committee for the Relief of the Black Poor. This was an attempt to help black people living in London who had been victims of the slave trade. Simon Schama has argued in Rough Crossings: Britain, the Slaves and Empire (2005) that the harsh winter of 1785-86 was one of the factors that encouraged Hanway to do something for the significant number of Africans living in poverty: "In the East End and Rotherhithe: tattered bundles of human misery, huddled in doorways, shoeless, sometimes shirtless even in the bitter cold or else covered with filthy rags."
Granville Sharp came up with the idea that this black community should be allowed to to start a colony of free slaves in Sierra Leone. The country was chosen largely on the strength of evidence from the explorer, Mungo Park and a encouraging report from the botanist, Henry Smeathman, who had recently spent three years in the area. The British government supported Sharp's plan and agreed to give £12 per African towards the cost of transport. Sharp contributed more than £1,700 to the venture. Others who invested in what became known as the Sierra Leone Company, included William Wilberforce, Thomas Clarkson, Samuel Whitbread, William Smith and Henry Thornton.
Richard S. Reddie, the author of Abolition! The Struggle to Abolish Slavery in the British Colonies (2007) has argued: "Some detractors have since denounced the Sierra Leone project as repatriation by another name. It has been seen as a high-minded yet hypocritical way of ridding the country of its rising black population... Some in Britain wanted Africans to leave because they feared they were corrupting the virtues of the country's white women, while others were tired of seeing them reduced to begging on London streets."
Granville Sharp was able to persuade a small group of London's poor to travel to Sierra Leone in 1787. As