CANADA is an integral part of the British Commonwealth unless the people of CANADA decide otherwise.
Which is why Canada went to war in 1939, while it took Pearl Harbor to get into it.
Of course Pierre Trudeau at the time was against it, he actually thought the Nazis winning would be better for French-Canadians.
Also, if the British Isles had fallen, the Government and the Royal Family would have relocated to Canada to continue the fight from there.
Perhaps the folks of Quebec might have other ideas?
Their secession efforts got shut down a few times—but the Canadian government used a combination of carrots and sticks to hold them in line.
It was like an abusive husband keeping the marriage intact with a combination of fancy gifts and occasional beat-downs.