An informal group of six Quakers pioneered the British abolitionist movement in 1783 when the London Society of Friends ' yearly meeting presented its petition against the slave trade to Parliament , signed by over 300 Quakers . They were also influenced by publicity that year about the Zong massacre , as the ship owners were litigating a claim for insurance against losses due to more than 132 slaves having been killed on their ship . The Quakers decided to form a small , committed , non-denominational group so as to gain greater Anglican and Parliamentary support . The new , non-denominational committee formed in 1787 had nine Quaker members and three Anglicans . As Quakers were non-conformists and were debarred from standing for Parliament ) , having Anglican members strengthened the committee 's likelihood of influencing Parliament
Zong massacre
Zong massacre
Society for Effecting the Abolition of the Slave Trade