With respect, Christopher, you can call yourself anything you wish, but the fact remains that Great Britain was and is the combined countries of England, Scotland and Wales. I have never seen any reference to the United Kingdom of England, Scotland, Wales and Ireland/Northern Ireland.
I don't intend getting into a political debate about this. I am merely pointing out that my own parents whose known ancestry was 100% indigenous Irish and who were born before Irish independence would have been deeply offended had anyone told them that they or their parents were British - just as offended, no doubt, as anyone born during the WW2 occupation of the Channel Islands would have been had they been told that they were German.
Like an earlier contributor, I don't want to be pedantic, but out of respect for the many Irish people who endured great suffering in the name of Irish freedom I feel bound to point out that it is an insult to them (and offensive to me) to have them declared forever British. In common with countless other Irish people, I had forebears who served in WW1 and they were no less Irish than I am regardless of the prevailing political situation at the time of their birth.
And Neil, I feel fairly confident that any Irish person researching their roots is well and truly aware that the country was part of the UK during WW1. You would, indeed, be researching the British archives but that still wouldn't make the person British.