It was a van. It was on a part of the road I know very well and there are no permanent cameras. I know where it was because the time stamp is about 3 mins before I stopped for petrol and also made a phone call which I can see the time dialled.
It must have been in one of the rest bays/hard shoulder and I can only think that I was along side or slowly overtaking another car and the angle mean't I diddn't see it. I was just cruising along minding my own buisness really. A van/piece of a van in the hard shoulder is normally nothing to worry about.
I think that what Mega says is true about the revenue generation. To put a temporary camera van on the three lane part at the top of the A3 and do people for going just over 80 is a bit desperate really but I was speeding so I will have to do the time.