So, i wasnt caught speeding.
To be clear as i was hastily typing as driver is a bit distressed - the driver was overtaking an old transit type van (open backed) carrying scrap metal. It looked to be overfilled, it had braked sharply, which the driver thought was due to something becoming loose. They have sped up to over take, and then saw the reason for the van braking in the first instance, which was the mobile unit.
Its become clear the NIP was sent to the lease in time, so they have no recourse this way. They are now facing 9 points (6 currently) amassed over 2 years and is obviously anxious now as their job involves visiting vulnerable people, so concerned about their job.
I understand speeding is speeding, having now had time for it to sink in, i dont believe there is anything they can possibly do.