We have a Royal Gwent Hospital and I was told by one of the nurses there that the site of the hospital is bestowed with the title and if it were to move it would cease to be call Royal because it only carries the title when it remains on the land it was bestowed on
I note that the London Hospital has turned lately into the Royal London, and that was because her Majesty waved her wand and said, you are Royal now, babies.
Ok Letter patent under sign manual - but thingey is better.