I’m following you guys from near Glasgow - you should look into the history of the Billy Boys, sectarianism in Scotland/ Ireland, Scottish football with Glasgow Rangers vs Glasgow Celtic (lots of Protestant/ Catholic influence), it’s one of the most heated sports rivalries in the world. The ‘Billy Boys’ song still gets sung.
I will say it’s an Irish actor playing a Scot & always sounds a bit off in film or tv when they do that.
Also, check out Mosley’s history too!