Pug - i think what you're trying to say is that the Police arrived after the other driver had left, or werent called to scene. The other driver had given his details correctly, and that it was a damage only accident, so he had left the scene.
The police cant act on 3rd party information and prosecute on it, so you saying that the other driver had no insurance at the time of the accident wouldnt stick. The police would have had no evidence that the other driver was even involved, would have been very easy for him to say that he wasnt had they tried to take him to court for no insurance. They'd need to catch him driving.
Im guessing this is the case, as had they caught him at scene with no insurance, im sure they'd have been sure to prosecute.