I would have to respectfully disagree with Ian. No colour is impossible to reproduce if research is properly conducted.
Fred Graham’s blue is 100% spot on. The other is too light, and that’s that.
A tiresome narrative was often propagated by some in the past that “sure, the GNR just went to a local paint shop and got whatever blue they had”; the implication being that the blue varied considerably. This narrative seems, as far as I’m aware, to have originated at Whitehead when 171 had its first repaint by the RPSI - which was way, way, way too light; in order to justify same.
Such a tale, apart from being utter, abject nonsense, is an insult to those who designed and maintained the very carefully nurtured corporate images of railway companies.
Each railway company (bar the smallest) employed people in their works, whose job it was to maintain “recipes” for paints and pigments to ensure uniformity and continuity. The last such at Dundalk was Marcus Bailie-Gage, whom I knew well; he was a very close family friend going back to when my grandfather was with the GSR in Inchicore.
Marcus went to the great big paint shop in the sky about twenty years ago, and though an extremely mild-mannered man, would have spat nails at anyone suggesting the GNR just used any oul blue paint!
Now, of course, blue is a primary colour and is notoriously hard to keep fresh, and daily coatings of coal dust, oil and oily rags didn’t help. But that’s a different issue; GNR blue was uniform.
The same, incidentally, applies to the two shades of CIE green, plus the oddly-titled “eau-de-nil” (“water of nothing”?) which they used for lining. The same narrative, “ah, sure, there were loads of greens” is again 100% completely wrong.
There were two.
1. Darker: Buses, lorries, station paintwork, platform wheelbarrows, coaches up to 1945, D class diesels when new, and steam engines which received green.
2. Lighter: Coaches 1955-62, and diesels repainted from silver circa 1957/8-1962.
But - especially the darker shade - it was applied to metal and timber surfaces, with varying degrees of exposure to weather, steam, hot oil, coal dust and filthy diesel fumes. Moreover, and perhaps far more importantly, it wasn’t renewed too often, as money was tight.
Thus, with GNR blue, CIE green, AND other liveries, there never were “multiple” variations of the livery, but there certainly were multiple variations of fading, weathering, and erosion of primary pigments. On CIE, many older vehicles in green were being photographed in colour for the first time when they hadn’t actually seen a touch-up paintbrush for a decade!
I’ll expound on this more when I get a minute. The issues around perception, especially (as mentioned above) amongst ageing male persons, is a wholly different matter.