Short answers, pulled from the story.
James Edward Oglethorpe banned slavery in the Province of Georgia in 1735. This decision marked one of the first official acts against human bondage in English colonial history.
Somersett's Case decided on the 22nd of June 1772 established that slavery could not exist under English common law without positive legislation. Lord Mansfield ruled this after James Somersett escaped captivity and was captured by Charles Steuart who intended to ship him to Jamaica.
William Wilberforce led parliamentary campaigns between 1789 and 1807 raising twelve bills to end the trade. Thomas Clarkson traveled thirty-five thousand miles gathering evidence at ports like Bristol Liverpool and London to support these efforts.
The Slave Trade Act passed Parliament on the 25th of March 1807 making the trade illegal throughout the British Empire. This legislation imposed fines of one hundred pounds for every slave found aboard British ships.
Nigeria and Bahrain remained the last British territories to abolish slavery until 1937. This date marked the final end of legal slavery throughout the entire empire spanning over a century of activism.