As an old white British man, he might think he has seen a lot, and he truly has experienced a lot in life..., in his comfort zone of the white community.

He probably thinks Africa is that whole continent...Like I felt perplexed some Americans chanted 'Go back to your country,' when they were also immigrants.

I guess you should say back to him, "Oh, so you are an expert in history. Would you mind telling me about British Nationality Act 1948?"