Erik HÃ¶glund biography here
Lovely colour, probably designed late 50s or early sixties, no idea how long they were made for. In the evening the blue wavelengths in light tend to be scattered more and the red wavelengths are more prominent so I would guess it may look more purple then. Different kinds of electric light can have varying effect too.
It is possible to change the white balance on some cameras for different light conditions, to give a better representation of colour. Check the manual for what options you may have and how to bend the camera to your will.
If you don't have a manual for your camera they usually can be downloaded (search using the make and model no of your camera).
Here's one in dark blue
, scroll down just below the blue plate.
Mmm, not sure that colour change explanation is correct.