I guess my point is that there is absolutely nothing in the photos to conclusively prove to ME that I passed under that exact gantry at 63mph.
Vehicle speeds are measured by a radar device mounted on the gantry support on the near side of the carriageway. When the device detects a vehicle exceeding the posted speed limit a photograph is taken of the vehicle. Since the camera is mounted on the gantry, facing the direction in which the traffic is travelling, the gantry will not be visible. This is the one which identifies your car. This is all the police need to secure a conviction. Your car will be identified, its speed will have been measured by an approved device and you will have provided the driver’s details.
However, another photograph is taken at the same time but taken from a point prior to the gantry. This takes a photograph of the speed limit displayed on the gantry at the time of the alleged offence. At the time this is taken your car will have passed the gantry, will be some way beyond it and it may or may not be visible in this second photograph (very often not). Without this the police could almost certainly still secure a conviction by producing in evidence the records held by National Highways which record the times that variable speed limits were imposed, but the photograph makes that unnecessary.
If you look at those two photographs you will see annotations on them which include the identity of the location (which will be the same), the time they were taken (which will also be the same), the time elapsed since the limit was imposed, the speed recorded by the approved device together with an image of your car
What further proof would you be looking for?)
