The battle of the colour brown appears to have been resolved in my favour.
Himself has sent me a snap of the current state of progress with painting 105 & 106 to see if I approve.
I understand he borrowed another pair of eyes to choose the colour and picked something described as 'German camouflage red brown'.
Frankly I don't care what it's called, I'm just relieved that this time it looks like something made of wood rather than the distinctly pink hue that ended up on 11 & 12.
Speaking of which, I have employed some gentle persuasion and he says he's going to go over the offending areas on those carriages with this colour.
So I've got my way in the end.