Not sure if you are referring to me in this comment
"I really wish posters would stop comparing the UK to the USA. As if they have identical histories and identical modern day situations. They don't".
As I think I already clearly stated, the two countries have different histories. What they do have is very entwined histories and English colonists introduced slavery to what became the USA, of that there is no historical doubt.
From then until now, the UK has profited handsomely from the American economy. In fact we are still to this day the largest investor in the US. The US in return is the UKs biggest investor.
The UK is the single largest investor in the United States. British companies have invested more than$540 billionin the U.S., accounting for more than 15% of all inbound foreign direct investment (FDI).The U.S. is also the largest investor in the UK. American firms haveinvested nearly $750 billionin the British market, nearly a quarter of their total investment in Europe, and more than 12% of all U.S. FDI worldwide.
So we have been intimately and literally invested in the USA throughout it's history and all periods of its history: slavery, the Black Codes, Jim Crow. If we consider the USA a racist state, our own people have given it the money to prosper and enabled it every step of the way. Much of the time we directly funded the people and structures that made slavery possible.
To wave slavery off "as way back then, so irrelevant today" we cannot explain where the animosity toward black people comes from in the USA. If you start to trace the beliefs and behaviors of white people toward black people in the USA they reveal an unbroken line back to the days of US slavery and then back to English Colonialism.
White people were always free, as in mathanxiety's illustration of the woman in Central Park, to call the full force of the state down on a black person.