Richard, it seems a long time ago that I was working on producing a nicely stained undercarriage and to some it may seem like sacrilege, but this is what it looks like now!
As for the colours, it was really the Germans who went for the “flashy” paint schemes and very nice models they make too, perhaps the British were / are too reserved. In the photo of the Shuttleworth SE5a you can see how dark the PC10 is, this is a latter variation, some of the earlier ones were a lot lighter, but whatever base colour was used the red wheel covers are about as far as they usually went, although there are one or two examples of fairly bright “nose art”.
Of course as I’ve said on several occasions, PC10 was not a colour as such; it was the 10th variation of Protective Coating and consisted of several layers of clear dope, undercoats, etc., etc.