US neutral Gray

[Graham Boak]

Other sources say that US inspectors at the aircraft factories were not strict on the colour matches, certainly on Olive Drab as can be seen in many photographs.

Neutral Gray was intended to be neutral in hue, the term does not refer to the USA's early neutral posture in the war. It was quite a dark gray. Most of the later-war photos seem to show the fighters, at least, in a significantly lighter grey. For the 8th AF, this was often the RAF's Medium Sea Grey, although this is far from explaining all cases. MSG has a definite bluish tint.

Some very early aircraft were painted using stocks intended to match RAF Sky Blue, and this may be the very blue colour you are seeing. Early B-24s in the Middle East were known as "bluebellies" because of this.