You should be ok. As far as I know there are no camera vans in use in any Scottish force areas that have additional cameras fitted to them facing the rear or side. The officer (civilian or police) operating the camera equipment is an appointed officer of the court and as such can make a statement to go along with the photographic evidence as to vehicle index number. However, I reckon :-
A) He would have to be seriously quick on his feet to drag his backside up out of the chair he was sat in when he first spotted you and head to a position whereby he could read your rear plate as you passed him.
B) At about 78mph your not going to warrant the above response from the camera operator. If it had been 150mph then it may have been a different story.
I wouldn't sweat it m8. I've had the same thing happen to me at a higher speed and I didn't get the dreaded brown envelope dropping through my letterbox afterwards.