Colour is difficult to get right. I thought the blue of the IRM Mk2b NIR blue and grey coaches was too dark. Upon investigation I realise that it perfectly matches the MIR 'NIR light blue' paint which was professionally colour matched to actual NIR paint in the early 1980s.
Despite this it still looks darker than my recollection. Photographs don't help as there you will find a whole range of blue shades.
For my own interest I repainted two IRM coaches. One with a lighter blue stripe, and the other in NIR maroon and dark blue.
This is the result.
I think the repaint is closer to my memory but maybe a bit light, so further experimentation will follow.
The MM GM also looks on the light side and I may repaint that if I can get the shade right.