The majority of Canadian history? The Liberals have ruled for 70 years in the 20th century, and 15 of the last 24 of the 21st.
Also the beloved and so mourned recently deceased Brian Mulroney, a Conservative, came from.... the same incestuous Laurentian Elite from the YYZ-MTL corridor that all of the PMs except Harper (whom I dislike, but I digress) have hailed from.
In fact, Im old enough to remember Mulroney's government collapsing because of corruption surrounding the same companies, the same industrialists, that discredited Chretien's (whom I liked, for what it's worth), and would have take down Jr's were it not for him firing the justice minister.
As to the not withstanding clause, you're really clinging on to "only separatists and conservatives have used it" without addressing all the reasons the Federal government doesn't need to ever invoke it (power is concentrated in the PM hands in a way unparalleled in the West)?
Look, I've read Trudeau's autobiography. His "memoirs" as he called it. I recall vividly his lament that a flawed constitution is better than none. Flawed? It fails at its most basic task - limiting government power.