This rates right up there with “what color is US Olive Drab?”, but … On my list of Spit kits is Airfixs Mk Vbt, AB264. Info I’ve seen she was shipped crated to Gibraltar , assembled, loaded on HMS Eagle. I have seen refence that she was repainted in Gibraltar or on Eagle with Extra Dark Sea Grey over the color used with the Dark Earth. Some sources say she was Dark Earth/ Middlestone from the factory. If true, wouldn’t the underside have been Azure Blue? (And I thought the “desert” scheme was done at depots in Egypt.) Some sources give the underside as Sky, but wouldn’t that point a finger at Dark Earth / Dark Green scheme from the factory? Thoughts?
I did my quest for Malta Blue Spits a few years ago. Built the Sword kit 70th Anniversary battle over Malta. I did my Spit with the S/N of BR-321 GL*J flown by Flt. Lt. Johnny Plagis. I found that this Spit was crated up and shipped from Glascow to Gibraltar May '42. There it was uncrated and assembled. She was in her Mediterranean paint scheme. There she would have been re-painted (more like painted over) into a grey color. Since she was at a British base I would not think any US Navy paints were used so I chose to use Dark Sea Grey. She finally made it to Malta June '42 via HMS Eagle.
Here is a link from Brit Modeler from where my quest for the mysterious Malta blue Spit started.
Malta blue spitfires - Page 2 - Aircraft WWII - Britmodeller.com
Hope this helps