@Yellow Belly
The ruling is that the police have to send the NIP (notice of intended prosecution) witthin 14 days, if they don’t then they can’t enforce it, if they send it they then can take their sweet ass time and i think they have some crazy long time of 6 months or maybe 2 years to take it further, HOWEVER…. the 14 day rule only applys if they don’t try and send it, I have heard of cases where if the reg’d keeper isn’t upto date or if there is hassle due to a company car and the like then the 14 days can be over-ruled and the case still taken on.
Regarding getting off on the police calibration thing… be careful how and where you try it, if its a stationary camera then maybe worth a punt but if its in car then not a chance, as will be vascar or maybe off the police cars own speedometer which are classed as calibrated and thus fine. You will just “annoy” them.