I saw an episode of Doctor Who that showed a couple of black ladies in London during Elizabeth I's reign. In my mind it added both colour and veracity to the episode.
Black people in Roman Britain? Why not? Phoenicians hung out in Cornwall due to the tin trade, didn't they?
It could make for an absolute scorcher of a historical novel to have a black bloke from...where? Numidia maybe? Ethiopia? Upper Egypt? The Kingdom of Meroe?
Apparently Meroe was a centre for ironworking and had trading links with both China and India. With trade came travel.
Thanks for putting up that link. While of course, it's primarily about Renaissance and post-Renaissance England, it's the mention of black people being there in ancient times that really grabs me.