Apologies but when I see a post about speed cameras I always end up spouting the law. Yes this gun exists and is being tested but no one is sure whether it will actually be introduced. You see, the evidence from a speed gun is secondary evidence of the allegation of speeding - that is what the law allows. The primary evidence is the opinion of the police constable who must see the vehicle and form the opinion that it is speeding, and only then can he use the speed gun to corroborate that opinion. So the question has to be, how the hell can plod tell if a vehicle a mile away from him is speeding?