What’s the story with the all silver RAF B-17 for example?
Photo taken at Rockcliffe, Ontario, she is a 168 Sq RCAF B-17, the unit was specially formed to carry mail to and from service personnel stationed in the U.K. , the Mediterranean and Canada. They began the service in Dec. 1943.

A nice link — http://www.vintagewings.ca/VintageNews/Stories/tabid/116/articleType/ArticleView/articleId/469/Letters-From-Home-The-B-17-in-the-RCAF.aspx