well, here's a Desert Spitfire in the garb. Not a million miles away from the Britmodeller version IMHO. I think we have to remember that there was a war on, and different locations would have varying batches of paint (especially if a local repaint was needed). It was obviously blue, rather than the sky of the UK. If it's of any consequence, trying to match the colours of Victorian railway coaches, internal and external, is even more challenging.