Merry Christmas.
The Regency Period was in the first quarter of the 19th century. Any blacks in England at that time were probably slaves. Slavery wasn’t abolished in England until 1833, after the Regency period was over.
While I don’t watch this show it reminds me of the soap operas my Grandma watched in the 50’s. She couldn’t always recognize they were not a real life family. So real was her experience she would recount it for my mom.