By the 1740's slavery was beginning to be viewed as an offence against 'God's natural law' by a small but growing section of British society. Others, notably 'The Society of Friends' (Quakers), took up an anti-slavery stance on religious grounds as early as 1760. John and Charles Wesley, the founders of the Methodist Church, declared themselves against the slave trade in the late 1770's. By the 1780's, the Anglican Dean of Bristol, Josiah Tucker, and the Evangelical writer, Hannah More had become active abolitionists.

A former slave, Olaudah Equiano, who visited Bristol in this period was the first black African to publish attacks against the slave trade. In 1795, the poet William Coleridge gave an anti-slavery lecture in the city and Bristol-born radical Anna Maria Falconbridge argued for racial equality around that time.

Although the tide of public opinion was turning against slavery, there were still many with a powerful vested interest in its favour. Much of Bristol's prosperity was tied up with the trade, and the Merchant Venturers continued to support its continuation.

 

 
In 1787 a young clergyman, Thomas Clarkson, arrived in the city. He had become interested in the slave trade whilst studying at Cambridge University and had come to Bristol to gather evidence. Clarkson often felt his life was in danger in the taverns and grog shops of Bristol as he mixed with the crews of slave ships. From these seamen he was able to gather evidence of the cruelty of slave raids and the horrors of the Middle Passage.   He collected shackles, thumb-screws, mouth-openers, and other instruments of torture used on slave ships.

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When he exhibited these things many people were shocked and began to actively support the abolitionists in setting up committees all over England. One was even set up in Bristol. John Pinney and Richard Bright, two of Bristol's leading slave owners were furious and attacked Clarkson in the local press.

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In 1787, William Wilberforce had introduced in Parliament a bill to abolish the slave trade. At first it was thrown out, but Wilberforce and Clarkson did not give up. By 1792 the House of Commons agreed to end the slave trade after another four years, but war with France broke out and saved the planters for the time being.

Wilberforce and his supporters continued to press Parliament to free all slaves within the British Empire. Planters fought this tooth and nail. Sir Rose Price, a baronet, argued that slavery

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 ...was God's will for black men, and that they were treated kindly by their white owners. 

 

However, Sir Rose was an absentee landlord from his estate, Worthy Park, Jamaica, and did not know that his attorney, John Blair, was amusing himself by flogging ten or a dozen slaves before breakfast every morning.

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Four weeks after William Wilberforce's death in 1833, the Emancipation Act became law and it took effect from 1st August 1834. It marked the end of the plantation system. Many plantations were soon to collapse. Planters could not afford wages and black people did not intend to carry on working in the sugar fields and boiling houses. Many planters went bankrupt.