Why did Scots dominate early Canadian politics?

I'm reading Andre Siegfried's long-out-of-print The Race Question in Canada, which was first published one hundred years ago. Siegfried was a Frenchman with the ambition of being Canada's de Tocqueville.

One observation Siegfried makes is that the Presbyterian Scots, very much unlike the Methodist and Anglican English, had a sentimental attachment to the French as a result of the "auld alliance". So the Scots were able to enphasize their religious and linguistic linkages with the English, while keeping on relatively good terms with the canadiens.