Yes, it was repeatedly judged that there was no provision for the ownership of another human being in English Common Law, making slavery (in the sense New Worlders would have it) de facto illegal, as false imprisonment or something similar.
Very contradictory, these judgements were made at the same time slaves were being bought and sold, by Englishmen, on English territory…
In fact, most people were quite disgusted by the trade in slaves, and the slave-based economy of some of the colonies, but it was extremely difficult to outlaw, because so many rich and powerful people were making mint – directly or indirectly – from it. So basically, for the general population, it was “out of sight, out of mind.” That said, the ethics of how the British made money and ran their Empire were continually debated by the intelligentsia and parliament, and occasionally in the justice system.
Most at home strongly opposed it on moral grounds, but little could be done, for fear of alienating the colonists. America was renowned for being “Land of the Free” because of how little the British government interfered with their societies (compared to most other nations of the time, Britain really was a bastion of personal freedom).
For the colonists, that meant freedom to use slave labour, and to steal land from Indians, the fundamental drivers of the local economy in many parts. After the British banned expansion into Indian territory (amongst imposing other things), the colonists rebelled, to make their own “Land of the Free”, and promptly set about exterminating the Indians and conquering the entire continent.
It took a lot of moral pressure, and a civil war, for the colonists to give up their freedom to own slaves, and they still yet haven’t given up their freedom to unreservedly exploit all that lies within reach.