Many years ago, intending to reach the extreme bottom left-hand point of Ireland, and getting a bit disorientated in the usual mist, we encountered a warning sign which depicted a car going over a cliff. Below this, on the same pole, there was another sign, this one prohibiting U-turns.

In the bottom right-hand corner of England there used to be s sign pointing to both Ham and Sandwich, in that order. Maybe it's still there, as the two communities are only a few miles apart.