Clarkson's presence was key. For the first time, the Quakers had an Anglican ally. Although in later life Clarkson would describe himself as largely Quaker, he remained an Anglican and therefore able to campaign in public. He would also be the 18th Century equivalent of an investigative journalist, travelling tens of thousands of miles on horseback to interview sailors, examine slave-ships and publicise the truth behind the propaganda. One can only imagine how much greater impact his pamphlet based on his prize-winning essay might have had had he not chosen to publish it under the cumbersome title: 'An Essay on the Slavery & Commerce of the Human Species, particularly the African, translated from a Latin Dissertation which was honoured with the First Prize in the University of Cambridge for the year 1785, with Additions.'
It is thanks to Clarkson that the abolitionist campaign could produce measurements of slave ships and the spaces allocated to each slave. He gave the abolitionists the ammunition to overturn the pro-slavery claim that the slave trade trained the sailors who made the Royal Navy great, finding that instead 20% of each crew died on the journey. Clarkson's first journey, in 1787, also resulted in the recruitment of James Arnold, a doctor on a slave ship, who would be an invaluable source of information. Although Clarkson was intimidated and nearly pushed into the river by a mob of sailors in Liverpool - one of the largest slave ports in the world - he also found that Manchester had produced an abolitionist petition of 10,000 names, from a population of just 50,000.
The stress of his ceaseless campaigning would eventually cause Clarkson to have a mental breakdown, one that would take him several years to recover from.
Another new convert to the anti-slavery cause was John Newton, an evangelical minister and hymnwriter who had previously been a slaver. Newton was an influential member of the establishment, and remains famous today as the author of the hymn Amazing Grace.
Newton spent 11 years of his life at sea, having been press-ganged as a youth. In 1748, after surviving a storm at sea, he became an Evangelical Christian, though he would later claim he was not 'truly Christian' until 1749. In 1750 he returned to England to marry Mary Catlett, then embarked (literally) as a slave-ship captain1 making three triangular trips between 1750 and 1754 before ill-health forced his retirement. He continued to invest in the slave trade until his partner, Joseph Manesty, was declared bankrupt in 1764, the same year that Newton was ordained. Amazing Grace was written in 1772, but slavery was conspicuously absent from a comprehensive list of sins that Newton published in 1781.
In 1787, the year Clarkson joined the campaign, Newton spoke against slavery for the first time, publishing a tract denouncing the slave trade.
Wilberforce was a young Tory MP who had converted to Evangelicalism in 1785, taking John Newton as a spiritual advisor. In 1787, at the encouragement of his personal friend, Prime Minister William Pitt 'the Younger', he took up the abolition of the slave trade as a parliamentary cause.
In many ways, the abolitionist ideology clashed with Wilberforce's other beliefs. He was opposed to widening voting rights to include the general public, opposed to public theatre, trade unions or granting extra rights to workers, and was generally suspicious of any encouragement of political protest by the public. Although he was a founder member of the Society for Carrying into Effect His Majesty's Proclamation Against Vice & Immorality, and of the Society for the Prevention of Cruelty to Animals (later the RSPCA), he obtained his own seat in parliament through bribery. He supported greater rights for Catholics, but campaigned to make evangelism a condition of the East India Company's charter. He was no supporter of free speech, and once had a bookseller jailed for stocking a book by Thomas Paine.
Wilberforce suffered from a mysterious stomach ailment that debilitated him for much of 1788, and meant that he took laudanum (opium and alcohol) until his death. Although his personal commitment to abolition is unquestioned, his capability as a leader was doubtful, and he was frequently outmanoeuvered by opponents or made unforced errors that allowed early chances to abolish the slave trade to be missed. In later life, he opposed the emancipation of the children of slaves and the immediate banning of slavery, preferring slow change.
Equiano's origins are somewhat controversial; he claimed to be a prince, born in Essaka to the Igbo (or Ibo) people, though others have disputed this. What is not in dispute is his remarkable life. Sold into slavery under the name Gustavus Vasa, he served in the 'Seven Years War' from 1756 to 1763 on several ships and under several owners before buying his freedom in 1766. He remained in the Navy, serving alongside a young rating called Horatio Nelson and becoming almost certainly the first African to visit the Arctic. He was instrumental in exposing the Zong scandal and became an ardent anti-slavery campaigner. He wrote his autobiography, and became a society figure as he toured the country many times to promote its various editions. He married in 1789, though we know little about his wife other than her name, Susanna.
An eccentric aristocrat and idealist, Sharp was another of the driving forces behind the abolition campaign. Like Wilberforce, Sharp was something of a radical, whose views can seem contradictory to modern minds. He came from a very musical family, and was a renowned singer, as well as being able to play several instruments. He supported the widening of the right to vote and supported US independence (he resigned his role in the Ordnance office over the War of Independence); yet he was staunchly anti-Catholic and anti-Jewish.
He was one of the earliest anti-slavery campaigners, taking up the case of former slave James Somerset in 1772. Somerset arrived in Britain with his owner, Charles Stewart, but sued for his freedom. The judge decided that laws pertaining to slavery did not apply on the British mainland, meaning that any slave who set foot there was instantly freed. Although the judgement pointedly avoided declaring slavery illegal in Britain, it gave a public perception that this was the case, and slavery on the British mainland effectively died out.
Sharp remained a prime mover in the abolitionist cause, setting up a colony for freed slaves in Sierra Leone, mostly using the former slaves in Nova Scotia who had been freed during the American War of Independence. In his later years, he became obsessed with the idea that this colony (which he never visited) should be run according to a system called 'frankpledge', based on how he believed the ancient Europeans to have ruled. His attempts to manage the colony from Britain were often disastrous, as he clearly had little understanding of the problems it faced and would send totally inappropriate supplies or orders.
Stephen was a lawyer who left Britain to try to make a living, a move that was timely given his involvement at the time with two women, one of whom he married. He set up a practice in St Kitts, and quickly became appalled by the slavery he saw all around him. He was an invaluable source of first-hand information for the abolitionist movement back in Britain, and eventually returned to be instrumental in the legal wranglings that would finally lead to abolition.
Ramsay was another priest, and a former resident of St Christopher2. Upon returning to England, he became vehemently abolitionist. As a former resident of a slave economy, he was regarded as a traitor by the slave-owners, and was subjected to a series of personal attacks and slanders over several decades. Many believed that he was hounded to his death by the pro-slavery lobby, making him one of the very few white martyrs to the abolitionist cause.
The founder of the pottery dynasty and grandfather of Charles Darwin produced one of the emblematic images of the abolition campaign, a medallion showing a chained, kneeling black slave with the slogan 'Am I Not A Man And A Brother?'.