Was it definitely a GATSO?
The flash time is fixed so it is fairly straightforward, but REDSPEED cameras vary the flash interval to suit your speed over the sensor,
and a distance of 10 meters between the two flashes should show an offence.
However in Cumbria, the SCP prosecute even when the distance is less than ten metres.
See this thread:
http://www.safespeed.org.uk/forum/viewtopic.php?t=15839 where the driver had only travelled 8 metres! Magistrates were quite prepared to convict him - until he got decent legal representation.
Many motorists simply pay up the £60 rather than fight the case costing time AND money.
They even used to show a pile of electronically cut and paste certificates on their website, to convince you they were properly calibrated!
They took them down soon after I revealed their shameful act in an FoI to the Home Office!
If you get a NIP, then come back with the details.
