I was taking a customer out yesterday and was in what I thought was a 40mph zone. I saw a police van and started slowing down (thought there had been an accident) and as I approached it I saw there was a speed camera in the back. I was doing about 35mph when I saw it (just under 40 before then), am I likely to get a fixed penalty notice in the post or am I likely to get away with it (they weren't pulling people)?