The first British Empire included many slave-owning regions, which were ruled by British appointed Governors. The West Indies and America*, were the most important. Most slave-owners had direct connexions with Britain and there was a constant flow of returnees for both family and business reasons. The lengthy journey meant they usually stayed for extended periods of time. Naturally they brought slaves with them as part of their household. Prior to the Sommersett case no-one had considered the possibility that British law could effect the property rights of slave-owners but the Mansfield Judgement changed all that. From 1772, slave-owners who brought slaves to Britain could be more or less certain that that slave wouldn’t return. London became a centre for freed slaves and a black community was formed.

British slave owners routinely brought their slaves to Britain as part of their ‘household’. This was unchallenged. No-one believed British colonial slave owners couldn’t continue exercising property rights here**. British jurisdiction was applicable in the colonies as they were Britain ‘over-there’. Colonial slave owners often had family connexions as well as business relationships and stayed for considerable periods. Steuart, who provoked the seminal case, was here for two years prior to Sommersett’s escape. Black slaves sometimes became quasi-servants in Britain, especially when they were ‘cute’ children, though once they were became adults they sometimes had a rude awakening and were shipped out to be sold.

Slaves in British households in 1745

The case which created London’s free black community was Steuart vs. Sommersett. Stueart’s slave Somersett wasn’t treated brutally. By the standards of a slave he had an enviable lifestyle. Steuart was outraged when Somersett ran away and decided to punish him by sending him to Jamaica to be sold. Sommersett faced a brutal future. Steuart never imagined that he couldn’t do this but it transpired there were legal objections. An early abolitionist, Granville Sharp, took up Somersett’s case on the grounds that British law didn’t recognise slavery. The 1772 case of Steuart vs. Sommersett concluded with victory for Somersett who was released (see addendum). Somersett won because British law hadn’t positively legalised slavery. Foreign law identifying Sommersett as a slave was irrelevant in Britain. Sommersett walked free, becoming a catalyst for a free black community.

It’s been estimated that there were about 25,000 slaves living in London in 1750, predominantly men. After Mansfield’s Judgement they were effectively freed. They moved to London’s poorer areas to live, where they often began relationships with local, white, women. The biological process of assimilation naturally followed. London was used to diversity and ex-slaves were treated well. Those who needed welfare depended entirely on charity, which was a bit hit-and-miss. Black sailors in the Royal Navy during the Napoleonic Wars were probably second generation black-British.

An ex-slave as a trusted companion to Dr Samuel Johnson, 1780s

The Mansfield Judgement wrote an entirely new view of slavery. Mansfield’s Judgement was social dynamite. He was quite aware of the impact of his judgement as he says that slavery is odious. Mansfield drew a distinction between Britain and the legal framework of the colonies. In brief, he legally separated Britain from the colonies. More importantly it gave impetus to the abolitionist movement as it moved socially and politically mainstream. Fifty years later British colonies were slave free.

ADDENDUM The key part of Lord Mansfield’s Judgement

The cause returned is, the slave absented himself, and departed from his master’s service, and refused to return and serve him during his stay in England; whereupon, by his master’s orders, he was put on board the ship by force, and there detained in secure custody, to be carried out of the kingdom and sold. So high an act of dominion must derive its authority, if any such it has, from the law of the kingdom where executed. A foreigner cannot be imprisoned here on the authority of any law existing in his own country: the power of a master over his servant is different in all countries, more or less limited or extensive; the exercise of it therefore must always be regulated by the laws of the place where exercised.

The state of slavery is of such a nature, that it is incapable of now being introduced by Courts of Justice upon mere reasoning or inferences from any principles, natural or political; it must take its rise from positive law; the origin of it can in no country or age be traced back to any other source: immemorial usage preserves the memory of positive law long after all traces of the occasion; reason, authority, and time of its introduction are lost; and in a case so odious as the condition of slaves must be taken strictly, the power claimed by this return was never in use here; no master ever was allowed here to take a slave by force to be sold abroad because he had deserted from his service, or for any other reason whatever; we cannot say the cause set forth by this return is allowed or approved of by the laws of this kingdom, therefore the black must be discharged.
https://en.wikipedia.org/wiki/Somerset_v_Stewart

*Pre 1776
**It wasn’t wishful thinking that their property right would continue in Britain as there were many instances of slaves being sold in London prior to 1772. So far as any could see the situation in London was legally identical to that in the colonies. See http://www.historytoday.com/james-walvin/black-people-britain-eighteenth-century

Baptism and literacy also featured heavily in the changes that occurred see Equiano’s autobiography go to http://www.gutenberg.org/cache/epub/15399/pg15399.epub?session_id=7f8d17c27fa783332a6fd1b038808056fd8588de