“Flower of Scotland”, along with “Scotland the Brave”, is an unofficial national anthem of Scotland. The introduction of “Flower of Scotland” in 1967 was partly due to hostility amongst rugby and football fans toward the British national anthem “God Save the Queen” being used to represent Scotland. It was finally brought in as an unofficial anthem in response to “God Save the Queen” being continually drowned out by the ferocious booing and whistling of some of the Scotland supporters.
Tune info from: Behind the Tunes, Vol. 1 by Dr. Peter L. Heineman