I'm wondering how long was it before we could say that a majority of people in Britain knew of the existence of Black people?

I would imagine that there were Black troops as part of the Roman forces, but as a minority? And given the Roman Empire spreading to Africa, the existence of Black people would be known there.

But given the lack of education of the masses, was this widely known? Something known in more elite circles? Would it be when the British Empire began its expansion? Or as late as the start of mass education?

To be clear, I'm not asking when the existence of Black people was known to a few people. Rather, at what point would your average peasant farmer have known that Whites were not all there was in the world?