The abolitionists regularly lobbied Parliament and put forward bills to abolish the Transatlantic Slave Trade. Another tool that was first used by the abolitionists was the mass petition. Submitting petitions to Parliament clearly demonstrated the strength of public opinion and showed just how many people opposed the trade. At one time, just about every town and city in the country organised a petition.
The first major campaign was in 1787-8, in which over 100 petitions containing 60,000 signatures were presented to Parliament in just three months. Then, in 1788, Olaudah Equiano led a delegation to the House of Commons to support a William Dolben's bill, to improve conditions on slave ships, by limiting the number of enslaved Africans that ships could carry. He was consulted by Dolben, MPs and the Prime Minister, as the abolitionists attempted to introduce a law banning the Slave Trade.
In 1789, Wilberforce made his first speech to Parliament putting forward twelve propositions for abolishing the trade. However, supporters of the Slave Trade used delaying tactics, asking for a new inquiry. They employed lobby groups and even produced witnesses to speak in their favour during the parliamentary debate. For example Captain James Penny described how well the slaves were treated on board ship. "...They are then supplied with Pipes and Tobacco ... they are amused with Instruments of Music peculiar to their own country".
The first time a bill was introduced in 1791, Wilberforce lost the debate by 163 votes to 88. After the bill was rejected, the abolitionists flooded Parliament with petitions. By 1792, they had presented 519 petitions with over 390,000 signatures, showing that public opinion was turning against the slave trade. Clarkson organised witnesses and evidence for the House of Commons committee hearings.
A bill to cease the Slave Trade was passed in the House of Commons in 1792 - but with the amendment that the ban should be 'gradual', which effectively meant 'never'. A change in political tactics led to the first breakthrough in 1806, when James Stephens advised Wilberforce to propose a ban on British subjects participating in the Slave Trade with France and its allies. Britain was at war with France and this made it difficult to oppose the proposal, without seeming unpatriotic. The bill was passed, limiting the Slave Trade by about a third and paving the way for the Abolition Act, which was finally passed on 25th March 1807, abolishing the Slave Trade in the British colonies.
The end of the Transatlantic Slave Trade, however, did not see the end of slavery and abolitionists continued to lobby Parliament for a total ban, which was not achieved until 1833.