Quoted in Fry's The Scottish Empire, the exchange between a census taker in 1861 and an old woman of Skye;
"Where are all the menfolk? This is an island of women and the elderly, where are all your young men?"
"Away running the Empire."
Looking at the details, it's true- Scotland produced an enormously disproportionate share of the military and civilian leadership of the British Empire, did very well out of it, and the Scottish upper class knew it.
Scottish radicalism comes from the working class who are not getting any proportionate share of the pie, or who feel let down by the total failure of the governing class to maintain pie, and tends overwhelmingly to the left;
there were a few xenophobic nutters who took the enemy of my enemy bit far too far, so anti- London as to be prepared to be pro- Nazi, but they (Hugh McDiarmuid being one) had the sense to keep their heads down.
It's like communist Middle America; it just isn't temperamentally possible, the place just doesn't turn out people like that.