And I thought it was the rozzers being niceI don't think you truly understand rolling radius and purposeful under clocking to prevent speeding.
If anyone's clocks genuinely read the correct speed I promise you 90% of people would get points in a week.
70 is usually about 65-67
85 about 81ish I think. Etc etc
Hence why police have to give a 10% leeway as everyone's clocks rarely read the right speed.
A satnav or speed App on a phone is the best way to prove the real speed.