Wow johnnyo, great work!
Thank you for this writeup, and all your hard work. So much good information here from the original poster and contributors.
I have a client/friend that likes pre-war cars, so this information could be very useful for dealing with 100 year old paint! (Most of the cars he has purchased have been repainted by this point, but he did have a 1913 Peugeot Bebe that we believe was the most original remaining example - it now lives in a museum in Denmark.)
And as for the 'poor' quality of the British paint, remember they were still coming out of war time even in the mid-50's.