Sargon is one of those pseudo pop-historians who works under the impression that if they talk slowly and authoritatively, people won't notice that what they're saying is riddled with inaccuracies or falsehoods.

While the figure of ~10% of households in Domesday Book being slaves is indeed accurate, this has little or nothing to do with William's legal codex, such as it was. It's also worth noting that Domesday was far from 'one of the first things William did', it not being carried out until a solid two decades into his reign. Mr of-Akkad's video makes the implication that William banned the slave trade in 1066 and this ended slavery, but a law that takes more than 20 years to start to reduce the occurence of the phenomenon it was supposedly banning is clearly not a law being enforced, if, indeed it existed as presented in the video.

We have staggeringly little evidence of any legal code at all dating from the reign of William I. In fact, we have very few surviving charters either. Given England's well established tradition of extensive legal codices, William and his immediate successors appear to have been happy to keep the majority of English law based on precedent, changing individual laws here and there, before a new legal framework appeared properly in the mid-12th Century. One charter of William I to the burghers of London simply exhorts them to keep to the laws as they were in the reign of King Edward. The Leis Willelme, the codex from which we purportedly get William I's declaration against the slave trade, has been dated to approximately 1120-1150, some 30-60 years after William I died. The reign of Henry I saw the publication of a number of putatively 'eleventh century' legal codices including the supposed law codes of Cnut, Edward the Confessor and William I, as legal scholars attempted to establish a corpus of precendence for new Common Law, based largely on what they thought the law had or should have been.

Neither did William I actually ban the slave trade. He specifically proscribed the sale of slaves out of the country. That wasn't a new law; it first appears in the 7th Century legal code of Ine of Wessex some 400 years previously,' where it stands in contrast to preceding Kentish law codes which suggest that a thief caught in the act should, in fact, be sold out of the country into slavery. The law prohibiting the sale of slaves out of the country supposedly ascribed to William I was therefore in place for four centuries in which the Early Medieval slave trade was at its peak.

The eradication of slavery in England appears to have occurred at some point between about 1102 - 1120 and is commonly attributed to Wulfstan, Bishop of Worcester. Wulfstan, according to William of Malmesbury, preached continuously in the port city of Bristol, at the time the leading slave trading hub in England. There, largely through sheer force of will, Wulfstan was supposedly able to turn the city's population against the trade, precipitating a wider abolition.

The abolition of slavery in the 12th century frankly bears little relevance to the discussion of British culpability in the transatlantic slave trade, beyond a rebuttal to those current commentators who say things like "well it was acceptable in the past so we can't judge it."