I have yet to research your sources, but the important thing is we seem to agree in principle; wealth inequality and greed is the root of the problem.

The important thing on dates is not so much when things were legislated, but when they were enacted.

I found this story quite revealing.

https://amp.theguardian.com/world/2015/jul/12/british-history-slavery-buried-scale-revealed

Indeed, the physical slavery that came to the US probably mostly came from England, just as we surely got it from Rome, like some kind of disease.

But the one thing that has been common is the now worldwide financial system of debt and inequality around enslavement, which now may fail if its number is truly up, the last thing we want to do is replace it with more of the same.