Chart of the world, on Mercator's projection, illustrative of the impolicy of slavery.

Scarce colour-coded map concerning the sugar trade and its link to slavery.

The section shaded yellow is the appropriate climate for the growing of sugar. The section shaded red is the area from which Britain may obtain sugar cheaply (parts of South America and the West Indies under British rule). The blue section shows where Britain is unable to obtain sugar due to the devastating effects of the slave trade. The pink and green areas are those from which the sugar trade is limited by high duties and restrictions. The argument is that the duties and restrictions are there to protect the slave trade and ultimately damage the British economy.

James Cropper was a successful and wealthy Quaker merchant, philanthropist and disciple of Adam Smith. A major force in the anti-slavery movement, he believed that eliminating tariff protections would lead to the end of slave labour in the West Indies. Cropper himself interests in East Indian sugar and therefore stood to benefit from the reduction of tariffs, which colored his role in the abolition movement. Nevertheless, 'in Cropper's mind the intensity of Quaker Quietism had fused with the economic optimism of Adam Smith. Anti-slavery confirmed this union, endowing laissez-faire with an immediate moral and spiritual purpose, and enriching his faith in the inevitability of human progress' (Davis, James Cropper and the British Anti-Slavery Movement, 1961).