Wyverns!

At Skipton Castle, Yorkshire.

Aggilators? In Northern England?

Now when I was a kid, I was quite sure that scaly crocodilian monsters lurked under the bed and in the dark, waiting to seize the unwary child in their yellow, foetid, unbrushed teeth. So, if you needed to get out of bed in the night, you had to (quietly) roll back the sheets, gather up your knees, and leap, as fast and as far as possible, landing with a slap to the light-switch by the door, because, as we all know, monsters are seared by light, and must snap instantly back into the shadows.
This sign reminded me of my old adversaries. I was in the car, and you're always safe from monsters in the car, so long as the doors are locked and the windows tightly rolled up....
Unless, of course, the monster is of godzilla-like proportions....And this sign wasn't very helpful. I'm not sure if they meant the whole alligator, when raised, was 4.5 inches high.... Or its individual, yellow, unbrushed, foetid teeth. Eek. They'd easily bite through a tyre. I looked around carefully. A few people were returning to their cars. The young woman carrying the box of papers and wobbling on her heels seemed to be pretty good bait for the alligators, I figured they'd go for her rather than try bite through the steel to get to me. Phew. Next time I'll park in a different car-park.