The original question was who was the greatest British guitarist. Anyone born in Northern Ireland is British by nationality. In this case Rory was not in fact born in Northern Ireland, so he was not British by nationality.

It’s a common mistake to confuse geography with nationality. But always best not to. Great Britain is an island, and it’s the largest in the group of islands known as the British Isles. Ireland is the second largest island in the British isles.

The term “Britain” is more of a concept than a place, and has been historically difficult to pin down. Further than that, Britain and British are not interchangeable. Most would agree that Northern Ireland is part of Britain.