Hi,
Have felt a bit insecure after posting the answer so just googled and found this that relates to close to where I live, cant find any trace of legal action being taken by speeding anywhere,GoodLuck..;-
We use several types of interactive signs on Kent's roads. These signs help us to increase road safety.
What is an interactive sign?
An interactive sign, also known as a vehicle activated sign, is a sign that reacts to the behaviour of drivers.
If a vehicle is moving faster than the speed limit, or if approaching a hazard, such as a bend, at an inappropriate speed, the sign will be activated.
Currently, there are around 145 signs around Kent, the majority of which remind drivers of the speed limit.
Speed limit reminder signs
The interactive speed sign is used to tell drivers that they have not reduced their speed, after entering a lower speed limit.
Signs are placed 100 to 250 metres after the start of a lower speed limit. If a vehicle is travelling above the speed limit, a radar beam triggers the sign. When this happens, the speed limit is illuminated on the sign and flashing amber lights come on above and below that sign. The sign remains illuminated for 4 seconds.