Blackstone had a few things to say about slavery in 1765:

Upon these principles the law of England abhors, and will not endure the existence of, slavery within this nation: so that when an attempt was made to introduce it, by statute 1 Edw. VI. c. 3. which ordained, that all idle vagabonds should be made slaves, and fed upon bread, water, or small drink, and refuse meat; should wear a ring of iron round their necks, arms, or legs; and should be compelled by beating, chaining, or otherwise, to perform the work assigned them, were it never so vile; the spirit of the nation could not brook this condition, even in the most abandoned rogues; and therefore this statute was repealed in two years afterwards. And now it is laid down, that a slave or negro, the instant he lands in England, becomes a freeman; that is, the law will protect him in the enjoyment of his person, his liberty, and his property.

The colonies, of course, were a different matter.