David,
Thanks for bringing up this interesting subject. Like you I have spotted this field conversion - at least that's what I think it is - in pictures before. Once you really start looking it turns out there are more than expected.
As far as I know only the Windsor Carrier was manufactured with proper weather protection, most likely because of experience in the field with other Carrier types. I wonder if it was a typical Canadian feature?
__________________
Regards,
Hanno
--------------------------
|