Edwin,
It does not appear that the War Establishment that you are searching for is available online, but the Library and Archives Canada entries are:
The Army Headquarters version of the file:
http://central.bac-lac.gc.ca/.redire...42993&lang=eng
The Canadian Military Headquarters version of the file:
http://central.bac-lac.gc.ca/.redire...78571&lang=eng
I have never attempted the process, but at the bottom of each page there are instructions for ordering copies of these files.
Colin