Octane Rating of Canadian WWII vehicles

[Dan Martel]

In researching why, during the Normandy campaign, the British Army received 1,400 trucks (Austin K5's) that were not operable and had to be scrapped, I found myself enmeshed in the minutiae of octane ratings, compression ratios and the difference between American and British made engines. Which leads me to my question about Canadian manufactured trucks.

As Canada was supplying trucks and cars to the British Army as well as to the Canadians in Britain from the beginning of the war, and the British Army was using low octane fuel up till 1943 exclusively, were the aforementioned vehicles that arrived in Britain early in the war operating on British Army low octane fuel or North American high octane?

And, if low octane, when did Canadian manufacturers change over to high octane engines?

Thanks for any help,
Dan.