Here's a totally non-ambiguous statement for you and no, it's not our gate either. Obviously the owner would seem to have had some trouble with intruders and theft in the past.
The sign is big enough to stop anyone saying I didn't see or read the health and safety section in white, also there's absolutely no way way the small print would confuse you.
All he needs now is the same notice on the other side of the gate and a couple of Jack Russells to get the intruder running in the right direction, just before the lead starts flying.
Well, do you feel lucky?