I saw exactly the same thing in Portishead about 35 years ago. I made the mistake of saying I would be a witness. It was a BBC outside broadcast truck who hit this telehandler thing and took out the side of his box body. I was a witness for the farmer, he had driven up to the junction and BBC was muttering about right of way, the BBC driver was going too fast for his surroundings, the proof being that he couldnt stop or avoid the agricultural machine on a narrow country lane.
They say accidents dont happen, but they are often caused. the tractor was stopped yet the BBC lorry had kept his precious right of way.