POLITE NOTICE: You're Nicked

[Grahamm]

I am more concerned with the idiot pulling out in front of me who did not see me, so fake Police on the BACK wont help that. And the fake ploice is more likely to antagonise the driver behind you, like you said he is only 6 feet from your rear wheel so he has already established that he is a nob 

If you have to brake because of someone pulling out in front of you, you don't want to get some idiot slamming into the rear of them, so if you can deter them from doing so in the first place, that's a positive in my book.