I can't see what harm the camper was doing at all, up against the hedge, no crop damage, no forced entry, what was the farmers problem? I camp like that quite often, usually pitching after 10pm and off before 6am, the only time I've been approached by a farmer I thought he was going to kick me off, but only wanted to flog me some eggs (Which I bought, even though I had no way of cooking them)
I hope the farmer gets prosecuted.