[Rata]

From what's gone before on other sites re this particular subject W&P there doesn't seem to be any conclusive evidence. There was plenty of FAA Martlet (of a number of squadrons) activity in this theatre but most if not all the B&W photos of the Martlets that give rise to speculation and debate about desert paint schemes seem to be of 805 Sqn FAA. Their machines were of a diverted Greek order and it's generally agreed that they were finished in standard delivery scheme of USN Non Specular Light Grey overall. The first two photos would suggest that is the case. According to some sources they were subsequently given (in the field) an upper surface repaint of Middle Stone. Then (again allegedly) Azure Blue unders and then Dark Earth disruptive over the top (see third photo).
I tend not to dismiss totally interpretations of B&W photos because often it's all anyone has. And I think 'shade contrasts' of grey in photos can help a lot. For example there was a much greater contrast between say Dk Earth and Middle Stone than that of the standard FAA Dk Slate Grey and Extra Dk Sea Grey. Also Azure blue will always show as being darker than Sky Type S. Indeed Azure Blue is often of darker contrast than Middle Stone where the two colours meet on the lower fuselage. And there's ALWAYS inconsistencies as to whether aircraft painting was actually carried out to official specs on all machines in service even in the same squadron. Look at the 260 Sqn Kittyhawk line up in the fourth pic. The first two aircraft clearly have a much darker undersurface colour than the third. Azure Blue and Sky Blue perhaps? Who knows. And of course another factor that make or break guesswork (even educated guesswork) is the type of film used by the photographer. Yellows are notorious here with early orthochromatic film- look at the surround of the fuselage roundel in the first pic.

IMHO if you want to do your Martlets in a 'desert' scheme I say go for it. Yours will be among a sea of modellers/illustrators/decal manufacturers that have gone that way before you and if anyone comes along and says you're wrong then I would say: Oh yeah? Prove it sport.

Garry G