in the bigger and more recent scheme of things it's more of an appelation for supporters of the union
The union of what? King James VI of Scotland (the Stuarts) inherited the English thone, when Elizabeth I of England died without an heir. The truth of the matter is that the English did not like: -
1) A Scot ruling over them (racists) and
2) The Stuarts were prepared to allow catholics to practise their religion & the English court did not like that, because, since Henry VIII (Tudor) changed the to protestantism & declared himself the head of the church of England, he & his cronies had been looting (catholic) churches of their silver/gold and items of value & divided the spoils between them. This was something they did not want to give up.
In the time of Elizabeth (1558) & for decades later, catholics were persecuted in England & if anyone was caught hiding a priest on their property, the entire family was put to death. Many were put to death simply because they were catholics.
When the (mainly protestant) English occupied Northern Ireland, they treat the (mainly catholic) indigenous people badly. So badly that the hatred known as bigotry was here to stay.Today, Sinn Fein & their various cohorts are mainly catholic & the Unionists or loyalists are mainly protestant. This hatred has been passed down through the generations for centuries.
Later when Irish immigrants, came to Scotland, they brought the bigotry with them & they have been passed down from parents to children.
That's why we have bigotry in our country.