The flag of St. Andrew, the patron saint of Scotland. Blue with a white or silver diagonal cross reaching to its edges, this is the correct flag for all Scots or Scottish corporate bodies to fly to demonstrate their loyalty and their Scottish nationality.
Its proportions are not fixed, but 5:4 is suitable.
It is correct both to fly it with or instead of the Union flag. If both are flown they must be on separate poles, the Union flag being on the most important pole.