The members of the Clapham group were chiefly prominent and wealthy Evangelical Anglicans who shared common political and social views concerning the liberation of slaves, the abolition of the slave trade and the reform of the penal system, amongst other issues, and who worked laboriously towards these ends over many years, motivated by their Christian faith and concern for social justice and fairness for all.
The group's name originates from the members who had settled in Clapham, then a village south of London (today part of south-west London), where both Wilberforce and Thornton, the sect's two most influential leaders, resided and where many of the group's meetings were held, and particularly those attending Holy Trinity Church on Clapham Common, then surrounded by fashionable villas.
Henry Venn, the founder of the Clapham group, was curate at Holy Trinity (1754) and his son John became rector (1792-1813). Wilberforce and Henry Thornton, two of the group's most influential leaders, resided nearby and many of the meetings were held in their houses. They were encouraged by Beilby Porteus, the Bishop of London, himself an abolitionist and reformer, who sympathised with many of their aims. The term "Clapham Sect" was a later invention by James Stephen in an article of 1844 which celebrated and romanticised the work of these reformers.
The reformers were partly composed of members from St Edmund Hall, Oxford and Magdalene College, Cambridge, where the Vicar of Holy Trinity Church, Charles Simeon had preached to students from the university, some of whom underwent an evangelical conversion experience and later became associated with the Clapham Sect.
Lampooned in their day as "the saints", the group published a journal, the Christian Observer, edited by Zachary Macaulay and were also credited with the foundation of several missionary and tract societies, including the British and Foreign Bible Society and the Church Missionary Society.
After many decades of work both in British society and in Parliament, the reformers saw their efforts rewarded with the final passage of the Slave Trade Act in 1807, banning the trade throughout the British Empire and, after many further years of campaigning, the total emancipation of British slaves with the passing of the Slavery Abolition Act 1833. They also campaigned vigorously for Britain to use its influence to work towards abolishing slavery throughout the world.
Some of the group, Granville Sharp, Thomas Clarkson and William Wilberforce, were responsible for the founding in 1787 of Sierra Leone as a settlement for some of the African-Americans freed by the British during the American Revolutionary War; it thus became the first major British colony in Africa, whose purpose in Clarkson's words was "the abolition of the slave trade, the civilisation of Africa, and the introduction of the gospel there".:11 Later, in 1792, another of the group John Clarkson was instrumental in the creation of its capital Freetown.
The group are described by the historian Stephen Tomkins as "a network of friends and families in England, with William Wilberforce as its centre of gravity, who were powerfully bound together by their shared moral and spiritual values, by their religious mission and social activism, by their love for each other, and by marriage".
By 1848 when evangelical bishop John Bird Sumner became Archbishop of Canterbury, it is said that between a quarter and a third of Anglican clergy were linked to the movement, which by then had diversified greatly in its goals, although they were no longer considered an organised faction.
Other societies that members of the group founded or were involved with included the Anti-Slavery Society, the Abolition Society, the Proclamation Society, the Sunday School Society, the Bettering Society, and the Small Debt Society.
The Clapham Sect have been credited with playing a significant part in the development of Victorian morality, through their writings, their societies, their influence in Parliament, and their example in philanthropy and moral campaigns, especially against slavery. In the words of Tomkins, "The ethos of Clapham became the spirit of the age.":248
Members of the Clapham Sect, and those associated with them, included: