The artist of this painting is unknown, and the entire thing is something of a mystery as it’s also not known who any of the people in the artwork are. All that is known is that it was painted in 1658, but the black servant on the right-hand side might not be contemporary to that.
The National Trust explains that black servants were often painted, or over-painted, onto artworks to show that their masters (the word used by the National Trust) had global connections and substantial wealth. There’s no other evidence that the Bedingfield family ever had a black servant, so it’s likely that it is entirely symbolic. The addition of this figure also appears clumsily done, so it’s probably a later addition.