After over 25 years of legal driving - yesterday, I was flashed by a speed camera on the M42 - I was doing 68 mph at the time - I now face a �60 fine for what ? Speed cameras should go.............
Are you saying the limit was temporarily lower than 70? Or are you saying that you where not in fact speeding? If the latter the pictures will verify your speed and nothing will happen else it's 3pts + �60. It's possible that a variable speed limit was in operation or possibly a temporary one for road works etc.
The variable speed limits are displayed on illuminated signs on the gantries over the motorway lanes. Don't know if the M42 has these - parts of the M25 do.