McGrath I completely agree with you. I think some people think of them as not being British not only because of intermarriage but because the Hanovarians were supposedly not British. However the heir to Queen Anne was originally Sophia of Hanover who herself was the daughter of Princess Elizabeth of Scotland who was born in Scotland and brought up in Scotland then England. So even her grandson George I in modern parlance would qualify at playing for Scotland at rugby. In all the thousand years or so there were a couple of generations only who didn't live in Britain and that was about 300 years ago anyway!

But you are right. Whether the hereditary monarchy is a good thing or not is a pertinent question. Trying to suggest they aren't British is just a bit silly.