CWatson,
The observations were Allan Toelle's not mine and they were conducted on eight pieces of original fabric and one piece of aluminium. None of the pieces contained upper surface camouflage, only red over CDL ( the aluminium was only painted with red) even though they were studied microscopically. There were however clear traces of under surface blue.

It is hard to see in this photo but the lower longeron has a 20mm return of blue under surface camouflage which is very clear in a high resolution image.
The port side cross covers a greater area than the cross field. Allan assures me that great care went into his observation.
"We eagerly anticipated finding evidence of the streaked camouflage on both sides of the cross-field of the RCMI specimen. We anticipated that the camouflaged areas would correspond to the areas of darkened red paint. However, careful examination under the microscope failed to reveal any coating material other than the clear dope and red, white, black, and blue paint mentioned above. There is no streaked camouflage present anywhere on the RCMI specimen!"
I do not know where the other samples came from, I know one is owned by - or was - Dan-San Abbott, and the aluminium piece would have been upper surface otherwise you would expect under surface blue as it was applied to the fabric from those locations. I have also heard that the piece discovered by Alex Imrie in the IWM, from around the air intake (including the werks number and datum line) has no streaky camouflage under the red.
You are correct I did post the picture showing the rear side of the lower wing cross which is stained by green paint, at that stage I thought the aircraft must have been painted normally when it left the factory, it was only after I contacted Allan Toelle that I learnt otherwise.
Allan's study (partly published in Aero magazine I think) discovered that the red paint was made from Mercuric Sulfide extended with Barytes.
Langdon