Owing to the ambiguous state of the law of slavery in England in the early eighteenth century, it wasn't clear whether English common law countenanced the existence of chattel slavery on English soil - obviously it was kosher in the colonies - or whether getting baptized freed one from slavery, or whether slaves weren't really slaves but some kind of indentured servants. So planters from the West Indies basically took the King's Counsel to dinner, got them drunk, and had them issue a declaratory memo telling all the courts yes, no, and yes. The Yorke-Talbot Opinion "suggested" that slaves did not become free simply by setting foot on English soil (so planters could bring their slaves with them to England untroubled about whether they'd be able to leave with them); that becoming a Christian did not change a slave's legal status (despite the fact that their "heathen" nature was a popular justification for slavery); and that "slave" meant "slave" - property like a cow or a dog, subject to physical punishment and even "destruction" at the whim of the master, protected by none of the rules of villeinage or indentured servitude that had come to govern slavery in practice in England. No legal reasoning, no reliance on precedent, just wrote down on paper what the planters told them and those were the new rules (and these were the two most prominent lawyers in England at the time). So every time a lawyer had to fend off an action calling into question the rights of master over slave in an English court, counsel simply cited the opinion of the learned King's Counsel and that was that.
By the end of the eighteenth century, Lord Mansfield has overruled the Yorke-Talbot Opinion and the abolition movements in both England and the U.S. are in full swing. Olaudah Equiano and Ottobah Cugoano - both Africans who freed themselves from slavery - are vigorous anti-slavery activists, two of the first published black writers, and active participants in the legal debates over the legitimacy of the enslavement of blacks.
That's what I should be doing whenever I'm blogging. Like now.