The MP for Hull, William Wilberforce, had met the Society for Effecting the Abolition of the Slave Trade and, with the encouragement of William Pitt, the Prime Minister, agreed to raise their cause in Parliament.
In February 1788 the prime minister commissioned a report on the slave trade and the effects and consequences for British commerce. The report was undertaken by the Privy Council committee for trade and foreign plantations.
This was followed by a statement in the Commons by William Pitt on 5 May 1788. He said that he would raise the issue by moving a motion "That this House will, early in the next session of Parliament, proceed to take into consideration the circumstances of the Slave Trade".
Following a debate, which revealed divided opinion, the motion was agreed. During the debate, the MP for Oxford University, Sir William Dolben, suggested that some limited regulation should take place.
Dolben introduced a Bill on 21 May to regulate the numbers of enslaved Africans carried from Africa to the West Indies.
The Bill received Pitt's support, providing that the measure was temporary pending discussion in the next session. Dolben's Bill was passed after a series of debates, receiving Royal Assent in July 1788.
Thomas Clarkson, a member of the London Committee of the Society for Effecting the Abolition of the Slave Trade, drew up a plan of the Brooks slave ship, graphically illustrating the 16 inches (40cm) allocated to each person.
This plan was sent to every member of the Commons and Lords by the London Committee, who were lobbying for further debate. It was also distributed around the country where it had an immediate impact.