There is a rumour that John is descended from a first cousin of Bonnie Prince Charlie. The published evidence is rumoured to exist in a book called “The History of Armagh” or “Tales of Armagh” or something like that. However, this book was published in a limited edition over a hundred years ago and no one Garvin knows of has seen it or seen a direct quote from it.
From Boyle Bulletin #4, page 25. If this is true, than the spelling would have been Stuart at that time. Bonnie Prince Charlie (real name: Charles Edward Stuart, Dec. 31, 1720 to Jan 31, 1788) was the exiled claimant to the thrones of England, Scotland and Ireland. His grandfather, James II, had been deposed in the 1688 revolution. The Jacobite movement was trying to restore the family to the throne.