Harold Mahony, "who won the title in 1896, was born in Edinburgh", which, apparently, makes him Scots. While I cannot answer for Tony Blair, also born in Scotland, and whose football support is clearly given to England, I can confirm the Englishman who commanded British and Allied forces at Waterloo was not amused when it was assumed by someone that he was Irish because he had been born in Ireland.
"Not everything born in a stable is a horse," he responded acidly. Who can blame him? The late Queen Mother was always accorded recognition as a Scot and she was born in London. If the practice of making one's place of birth reflect one's nationality, Scottish regiments would have a problem with all the little Germans they brought home with them from the old British Army of the Rhine. My old headmaster was an Indian by this school of thought and many of my contemporaries, born in a rather more imperial age, would be Kenyan, Singaporean and so on.
Commentators should avoid making glib assumptions based upon where one's mother happened to be when she gave birth.
ANDREW HN GRAY