Being discussed on Pistonheads - apparent proof of a NIP under 10%+2
One single documented example from well over 6 years ago. Assuming that the NIP was genuine (and we have no reason to doubt it), it is clearly not indicative of any even vaguely widespread policy of enforcing below the ACPO/NPCC threshold, and also not in itself proof that enforcement occurred for a recorded speed below the threshold. From the lack of any other documented cases, or other evidence apparent in this case, it seems far more likely that the wrong speed was entered on the NIP - either as a straight typo, from copying the wrong line on a manifest, or from multiple pings from a mobile device, where the speed was taken from the "wrong" ping after the case was flagged for enforcement from the "correct" ping.
We had a case on PePiPoo some years back where the OP received a NIP for doing 103mph in a 30mph limit in the middle of Oxford in the middle of the afternoon - which the OP was adamant was not physically possible in the prevailing traffic conditions. The gatso photos showed a recorded speed of 35mph - so there was clearly a manual transcription error.