Hi David
I think a clearer statement could be made, canvas hatch covers were used in North Africa on some Patter 11 and 12.
I've reviewed many of the photos of North Africa that have been posted over the years on MLU and I can not find a sample, I do distinctly remember having seen a photo of improvised hatches with a canvas cover. Did find picture of a New Zealand Convoy with a Dodge in the foreground that appears to have a canvas hatch cover.
There most definite are examples of square hatches with the sun compass mounted on the roof, see below. There were a butch of color photos with Tan or Sand CMPs but non of them seem to have canvas hatches, though some canvas tops.
Did a quick search of the Australian War Memorial Archives search phrase North Africa, Truck, conflict WWII, which yields many photos in those that I looked at that clearly showed trucks with cabs the majority seemed to be solid tops with no hatch at all. But there are also a large number were the cab tops have been completely removed.
Interesting pictures to look through. Try a browse through
http://www.awm.gov.au/search/collections/?mode=advanced
Like this one
Searching the Imperial War Museum yields similar results in looking at the first 20 pages not surprisingly most of the photos showing CMP or Canadian Vehicles have been posted on MLU at one time or another.
But back to Bills original question concerning the Round Hatch on Pattern 13, does any body know when that was introduced?
Bill I am also looking for my notes on the detail of round hatch unit and when I find them will try and post them. Likewise with pattern for the canvas cover that I have as a cad drawing but have never been able to figure out how to post.
Cheers Phil