Slavery existed in England’s American colonies because the King, Parliament and English merchants profited from the trade. It didn’t exist in England.
It did for awhile, but they got rid of it a lot earlier than we did.
"In 1729 the Attorney General and Solicitor General of England signed the Yorke–Talbot slavery opinion, expressing their view (and, by implication, that of the Government) that slavery of Africans was lawful in England. At this time slaves were openly bought and sold on commodities markets at London and Liverpool.[56] Slavery was also accepted in Britain's many colonies. "
When England got rid of slavery but only in England Benjamin Franklin called out the Empire for it’s hypocrisy.
The letter is quite scathing actually.
https://freerepublic.com/focus/f-chat/3940983/posts