Thought after the outbreak of the war Churchill asked America to hold safe the magna carta. By 41, USA industries were tooling up and producing to support Britan and France (Think “lend lease” had started by then). Bill Knudsen’s advisory committee had managed to sow seeds that would turn into the production marvel that was the USA in WWII.
“Freedom’s Forge” ..How American Business Produced Victory in WWII By Arthur Herman.
KYPD
Magna Carta was deposited by the British with the Library of Congress for safekeeping after the World's Fair. For a time that and the most important American documents were stored a Ft. Knox.
While an interesting story, this sounds like a discussion in the War Cabinet that was never acted on.
The discussion about Americans not liking the British so much was very interesting. I'd just chalk it up to being a very difficult time for Britain before the U.S. entered the war.