Sneaking up behind me

I was in the field opposite the house watching them spraying the crops, thinking there might be a blip opportunity when I heard something that sounded like a Chieftain tank coming along the lane. It was this incredible piece of kit. I have no idea what it is designed to do, it might only have three wheels but it is not quite in the same league as "Trotters Independent Traders" yellow Reliant. The building behind is a converted chapel and, although not as tall as a house , is higher than my bungalow. That might give some idea of the scale of this beast. It just rumbled past and turned left at the end of the road.
I had to get the shot immediately or loose it so that's todays excuse for the quality of the shot.