I am afraid that your last response has devalued your previous answer.
In the 1970s - as I found to my cost, there were portable speed traps, often disguised as GREEN GPO (telecom) cable junction boxes. These were triggered by the passage of a vehicle over pneumatic cables that were laid across the carriageway.
Speeding excess, captured by mobile traffic offices in a car, was over a measured distance and verified using a specially calibrated ADDITIONAL speedometer in their vehicle.
this continued at least into the 1980s when I worked for the Talbot Motor company, with specific responsibility for the sale of cars to a number of Police Forces.
So, I am now dissatisfied with your earlier answer. You might (as I do not know your age) possible have travelled in a car in the 1970s or 1980s, but your answer shows that you do NOT have adequate knowledge of that period. Therefore I am unconvinced as to your actual knowledge to answer the question in hand.
If the stipulation that I am aware of DID exist in the earlier Road Traffic Acts, it can only cease to exist now, if those acts have been repealed.