In a development inspired by the testimonies of enslaved and formerly enslaved campaigners such as Ignatius Sancho and Olaudah Equiano, as well as British abolitionists like Thomas Clarkson and William Wilberforce, the official Act of Parliament abolishing the British slave trade was passed on March 25, 1807, to begin on May 1st of that year. Though landowners were still permitted to use their existing enslaved labor force (slavery itself wouldn't be officially outlawed in the British Empire until 1833 with the passage of the Slavery Abolition Act), this marked the first major success in the campaign to end slavery in the British Empire.