Odd sign

Puzzled by this sign found on my morning walk.

What is strange about it? Is it an Arnside version of Cerberus the mythological Greek and Roman dog. This had three heads a main of serpents and lion's claws. Seems unlikely. I am anxious to see it but as the sign is in the caravan park I may have to wait until better weather.

Of course if there was a sign on a house saying Warning Strange People I would have no difficulty in believing it.