I was born in England of English parents, but some time back the old ancestors were Irish, so should i claim dual nationality, no, that was then, this is now. Had I been born in Ireland, with English parents would that make me Irish, no still English as far as i know. It will always be an issue, because as been pointed out your granddad may have come from Jamaica, but the children were born here, then what are they, not English, but British, but that doesn't seem right either, give up.