The Steel Navy user "dick", Ian Gazely and myself did the paint guide for this kit.
It's first necessary to reiterate that 507B wasn't part of the Royal Navy's menu for some time prior to Op Pedestal, and even when it was in use it was Dark Grey, Home Fleet Shade. There is no evidence whatsoever to support it being a medium grey. It wasn't in use in 1941 though so let's say no .ore about it.
There are numerous photographs around of HMS Illustrious, and most of them show her around Op Excess when she has been repainted. We've been calling this the "high contrast scheme" which we believe was most likely 507A and 507C.
During Op Judgement there are fewer photographs and what ones do exist are generally poorer quality. However, we arrived at the conclusion that the camouflage pattern was essentially similar but for some detail changes we think we captured at least most of. It's a bit harder to tell as combined with the poorer quality references, the camouflage is dark and much lower contrast.
We cannot be certain of the paints used but the two most likely sets of options mean mostly the same thing to modellers. We recommended 507A and Equal Parts 507A / 507C Emergency Mix medium grey for it, and Bronze Grey for the flight deck. It's possible she wasn't painted in emergency mix medium grey but just had her new camouflage chalked out and the 507A camouflage repainted on top of weathered overall 507A scheme before having to put back out to sea.
With the hopefully imminent release of the Flyhawk 1/700 HMS Illustrious it the right time to hopefully clear up an issue of which I've been aware for a decade or two. P.S. Mine is on pre-order.
I am fully happy with my determination of her camouflage pattern at this time, including flight deck lining, however, I am still not 100% happy regarding the colours used.
Over many years of viewing debates on this issue, there appears to be two distinct determinations:
Firstly: 507B and 507C.
Secondly: Two locally mixed colours, fairly close, but different from 507B & 507C. The argument being that as Alexandria was at the end of the long Mediterranean supply chain, large quantities paint would have been very low on the priority list. Therefore local stocks were utilised in the various "Alexandria schemes", including the scheme applied to HMS Illustrious.
Any thoughts or suggestions will be gratefully received.