O Flower of Scotland (1974?) is now sung as the unofficial national anthem at many sports events by Scottish fans.
Also sung while the players stand to attention prior to the start of soccer and rugby games involving the Scottish team.
I now regard Flower of Scotland as my national anthem though its never been officially adopted as such.
We still sing the English national anthem on remembrance Sunday in recognition of our joint defence force (but only the first verse, due to the anti-Scottish sentiments expressed by later verses.)