However slavery elsewhere in the British Empire was not affected. Joseph Knight 's case in 1778 established a similar position in Scots law. Slavery was abolished throughout the British Empire by the Slavery Abolition Act 1833, with exceptions provided for the East India Company, Ceylon, and Saint Helena.or slavery in the present-day British Isles, see Human trafficking in the United Kingdom. Slavery in the British Isles existed and was recognised from before the Roman occupation until the 12th century, when chattel slavery virtually disappeared after the Norman Conquest and was replaced by feudalism and serfdom.