Blue paint under black

[Tom Bickerdike]

    Working on my ARQ Ruby black and original colour to what I know I keep finding blue paint under the black either by sanding/stripping back or behind trim such as the dashboard and door cards. Where the blue is exposed behind trim it appears not to be a finished colour and somewhat mat and looks quite thin. 

I didn't quite know what to think of this and one thought was it had the colour change in the factory? but today a friend suggested they may have used a dark blue base coat as general practice on black cars? Does anyone have any knowledge on this please. 

I had previously decided to spray the car blue and this feels like the car is agreeing with me!