There are several cases in which the verb tense change is optional.Originally Posted by yougen
1) when reporting something that someone has just said
Sarah: I'm tired from all that shopping.
Joe: What did you say?
Sarah: I said I was tired. OR I said I'm tired. ( I prefer this one.)
2) when reporting something that is still true
John said, "I love Mary."
John said that he loved Mary OR John said that he loves Mary.
3) when reporting a general truth or scientific law
Harry said, "The world is round."
Harry said the world was round. OR Harry said the world is round.
So, in answer to your question, I'd say that both forms are correct if he is still living and still English.
He said that he was English. OR He said that he is English.
I prefer the second option in all the examples, but the other form is also fine with me.