William Wilberforce, MP for Hull from 1780, took up the cause of abolition after meeting a former slave trader, John Newton. Wilberforce would become the Parliamentary mouthpiece for the campaign.
Born in Wisbech, Cambridgeshire, Clarkson was at Cambridge University preparing to become a clergyman when he entered and won the 1785 annual essay competition, the title set being 'Is it lawful to enslave the unconsenting?'.
During his research he learned about, and was horrified by, the transatlantic slave trade. It was then that he decided that something should be done.
Within a year Clarkson had given up plans to enter the church and had decided to devote himself full time to the cause.
In 1787 Clarkson became one of the original 12 members of the London Committee, which also included Granville Sharp and was part of the Society for Effecting the Abolition of the Slave Trade.
As the only Committee member without business commitments, Clarkson researched for evidence that could be laid before Parliament, and also promoted the cause nationwide.
He had earlier met many Quakers who were campaigning for abolition and when he travelled to all the major British ports, as well as cities and towns around Britain, Clarkson was supported by local Quaker groups.
His research was to prove crucial to William Wilberforce's subsequent work in the House of Commons.