Strong, Jonathan (c.17471773), de facto freed slave, was born, probably in Barbados, about 1747. Nothing is known of his early life until 1765, when he was brought to England by his master, David Lisle. The latter had read law at the Inner Temple and was admitted to the bar in 1747. Some time after 1757 he went to Barbados, where he was not successful and even sustained losses. He returned to London, bringing Strong with him. On 22 July 1765 Strong was baptized in the church of St Leonard, Shoreditch. Many black people erroneously believed that baptism made them free. It was possibly this act that caused Lisle to assault him severely and leave him in the street. He found his way to a house in Mincing Lane in the City of London, where William Sharp, a surgeon, treated poor people without charge. There, waiting in a queue of patients, he was seen by William's younger brother, , who was moved by his plight. Through his position at St Bartholomew's Hospital, William had Strong admitted and treated. He had been so badly injured that it was some four months before he could be discharged. The Sharp brothers found Strong a job with Mr Brown, an apothecary and surgeon in Fenchurch Street, where he was paid wages and regained his health.
By chance some time later Lisle saw Strong in the street when the latter was accompanying Mrs Brown in a coach and followed him home. By September 1767 Lisle had no work and was in financial straits. He decided to try to sell Strong to James Kerr, of Moor Park estate in Jamaica. Kerr refused to hand over the agreed £30 until Strong was delivered to him, so Lisle hired two men to seize him. Mr Brown was too intimidated by the thugs to prevent them from taking Strong to the Poultry Compter, a gaol in the City. Strong managed to smuggle out a letter to Granville Sharp, who obtained a writ of habeas corpus requiring Strong to be brought before the lord mayor of London, an ex officio magistrate, to determine the legality of his detention. On 18 September 1767 Sharp, Strong, David Laird, the captain of the ship on which Kerr had planned to transport him to Jamaica, and William Macbean, Kerr's solicitor, came to Mansion House, bringing Lisle's deed of sale on which Lisle's address was given as St James in Westminster. Lisle himself did not appear. Sir Robert Kite, the mayor, decided there were no grounds to commit the case to a higher court. He robustly declared that Strong had committed no offence and was free to leave. The captain attempted to seize Strong by force but Sharp prevented him and the city coroner, who was present, informed Sharp that he had grounds for bringing a claim of assault against Laird. Lisle subsequently challenged Sharp to a duel, which he refused. Kerr issued writs against Sharp for depriving him of his property, and the case rumbled on inconclusively until 1774, after Strong's death, when Kerr admitted defeat and paid costs.
The lasting legacy of Strong's case was that it inspired Sharp to study the law for himself. He concluded that slavery had no basis in English law, published a book detailing his arguments, and began his one-man campaign to get this legally recognized. He brought several cases similar to Strong's to court. None was conclusive until the case of James Somerset, which led to the decisive judgment in 1772 by Lord Mansfield that, as Sharp said, there was no legal basis for slavery in English law, whatever the situation in the colonies.
Meanwhile Strong played no further part in Sharp's work. He presumably went back to his life as Brown's servant. He died, probably in London, on 19 April 1773. What his reaction to the Mansfield judgment was, or whether he realized the importance of his role in it, is unknown. What is significant is that the mayor of London was certain that Lisle's claim to have sold Strong had no validity. He had no doubt that selling adults in England had no legal basis, whatever the ambiguity before 1772 about the position of slaves in England whose masters were only visiting from the colonies.
parish register, St Leonard, Shoreditch, 22 July 1965 [baptism] · corresp. and testimonies relating to the application of David Lisle, former solicitor to the Wine Licence Office, for the post of solicitor to the Board of Customs in America, 234 Sept 1767, TNA: PRO, North America Customs and Excise Corresp., T1/456/132145 · T. Clarkson, The history of the rise, progress, and accomplishment of the abolition of the African slave trade by the British parliament, 2 vols. (1808) · P. Hoare, Memoirs of Granville Sharp, esq. (1820) · F. A. Inderwick and R. A. Roberts, eds., A calendar of the Inner Temple records, 4 (1933) [David Lisle] · G. Sharp papers, Glos. RO
Glos. RO, papers of Granville Sharp, D 3549 13/3/38; D 3549 13/4/2 book G [also on microfilm/online from Adam Matthew]