OK, but does anyone have any idea whether the entire corpus of such songs actually backs the idea or not?

I'm not trying to start wars between England and Scotland, being a Geordie with a family from the Borders and a Scottish surname. I'm of the opinion that Northern English and Lowland Scots have more in common with each other than either have with the other denizens of their supposed countries. Come back Northumbria, in its original glory.

However, all these centuries of separation have to mean differences in the culture, and the culture is reflected in the songs. I can't imagine anyone on this board disagreeing with that.

And if the original comment was perhaps slightly barbed, a little gentle joshing across the border - in both directions - is not necessarily a bad thing in itself.