Originally Posted by
treadigraph
The first production batch of Spitfires was K9787 - L1096...
I recall seeing pics of Miles prototypes wearing U- plus four digits - eg Miles M.20 was U-0228. Anyone else do it and was it an Air Ministry concept?
It's explained here:
https://en.wikipedia.org/wiki/United...t_test_serials
Early in WWII they were modified to look like military serials, but it was the precursor to the later G-21- (for Miles) test registrations.