Got a speeding ticket but the image was taken from across the road on the other side.

I got caught doing 36 in a 30 zone which was a dual carriageway - I was matching speed of the cars in front, and I didn't see a police recording van. I checked the picture and it was from the other side of the dual carriageway and the picture was from the rear of my car.

Is there a law that the van has to be seen or anything like that? Or is this new tech so they can catch more people?