Few recall that the very slavery he speaks of was legal and normal under British rule. It took two revolutions to depose of it.
Slavery Abolition Act 1833
The Slavery Abolition Act 1833 was an 1833 Act of the Parliament of the United Kingdom abolishing slavery throughout the British Empire (with the exceptions "of the Territories in the Possession of the East India Company," the "Island of Ceylon," and "the Island of Saint Helena"; the exceptions were eliminated in 1843).