Thanks Peacoat I also thought it was the real deal but just wasnt sure with the feel of the material.
When I said 'taught' I mean I buttoned it and lifted the sleeves to get right under the pit and measured it likeso. Hence whilst it was held 'taught' but not overly tight. I'd say it would be a 18 had I laid it down and measured it without disturbing the fabric. I will take more detailed measurements later on and post them up. Any particular measurements you want?
There shouldn't be that much difference between the material in the WWII and the 1966 coat. Sometimes one finish will be a bit smoother than another, but usually that is only discernible when they are together side by side.
The p2p is the only measurement I need. Pull the fabric tight, release and then take the measurement. Disregard the seams and don't measure from them.