[Verginius Rufus]

I think Scottish Catholics are mostly descended from Irish immigrants over the last couple of centuries, fleeing poverty or starvation in Ireland. There were a few places in the Highlands that never became Presbyterian but I think the population would have been a minuscule fraction of the overall population of the country.

Doing some research in 17th-century Ayrshire (a hotbed of the Covenanter movement), I ran across a few individuals labeled as Catholics, but I'm not sure if they really were Catholics, or just perceived as such for not being zealous enough for Presbyterianism. Sir Walter Scott's novel Old Mortality deals with the post-Restoration Covenanters in that part of Scotland. They were harassed until the Glorious Revolution established toleration for all Protestants.

[Cronos]

The SKyeand Orkney Islands remained loyally Catholic

[the scotsman]

Ayrshireman born and bred here.