And your point is what exactly? What does it matter what a person's first cousin six time removed did? There will also be people ruling the country who have ancestors who were abolitionists and probably some who have slave owners and abolitionists in their ancestry.
You are going so far back as to be making meaningless points.
What about Tony Benn? He was born into the aristocracy. Has he been through a daft Left wing genealogical witch hunt exercise?