Didn't the movement to stop slavery come from the UK? After that happened the African region refused to stop because it made them rich so England had to invade and created the Ivory Coast? England has a lot of credibility.
The idea of reparations has come up. Should the US be paying or the African countries who profited and kept it going for another 100 years.
The British were engaged in the slave trade, then worked to outlaw slavery but replaced it with indentured servitude that was basically like slavery with a trivial income. That and exploitative colonial government meant you don't need slavery to loot everything.
Reparations are a different topic and wouldn't necessarily solve the problems of slavery/colonization.