Welcome aboard.
Cannot say I was closely watching the railway's doings at the time, embedded in a busy career and the general truck of life. My impression was 'the same yellow on road vehicles as loco fronts' but this comes with a note of caution: I am a divergent trichromat and as such my colour perception is slightly shifted from the modal perception, right in the zone relevant to this question!. Simple discriminator, I see the Sodium D lines as bright orange, whereas the modal perception is yellow.
Cannot say I was closely watching the railway's doings at the time, embedded in a busy career and the general truck of life. My impression was 'the same yellow on road vehicles as loco fronts' but this comes with a note of caution: I am a divergent trichromat and as such my colour perception is slightly shifted from the modal perception, right in the zone relevant to this question!. Simple discriminator, I see the Sodium D lines as bright orange, whereas the modal perception is yellow.