Have you ever spotted a blue light in the distance, thought it was an emergency vehicle, only to find it was a blue headlight or some such, possibly seen through a guard rail?
This morning I was approaching a roundabout when a white car with a blue light on the roof approached from the left. My initial thought, in those first few milliseconds, was "Police car", and started to brake to allow it precedence. I then realised it was not a flashing light but a solid blue baton light with the taxi phone number on it.
As soon as I got in I telephoned 101 and reported it. Blue lights on vehicles, other than emergency vehicles, are a big no no. The number of Volvo trucks with illuminated blue advertising signs on the back wall of their cab is infuriating too, but at least they are not as bright as this example was.
OAP rant over!