Bit disappointing to see that the OP has not come back to this thread.
The reason I asked for sight of the documentation the OP received is that I’m also involved in a couple of motoring forums, where periodically someone will claim that they were prosecuted for 71 in a 70, or 31 in a 30, or another speed not conforming the current ACPO guidance about at what point prosecution should commence. However, nobody has ever provided any evidence to support their claim.
I have no reason to disbelieve the OP; but if the OP were to share the (redacted) documentation, this would be the first definitive proof that this is actually happening, and which would be useful information to share in other forums.