It is indeed true that Mr. Mulroney was able to win most of the francophone seats of Québec in the 1980s. But it wasn't because the party had committed supporters, or because Quebeckers had decided they supported conservatism; it was because Mr. Mulroney spoke French like a francophone (the first such Tory leader since 1867), and the Liberals had an anglophone leader. The party bloomed, but the roots were shallow and were scorched.
It was like the Orange Wave in 2011.