Hangman's Crack

I looked over a wall and saw a old castle.
Running up one side of the wall was a long shallow groove. Half way up the groove ran a horizontal crack.
The groove continued to the castle battlements, about 100 feet high above the ground.
The groove was a sports rock climb, which ended at the horizontal crack.
On the wall beside me was a small green steel plaque giving details of the climb.
It was called 'Hangman's Crack' and graded Extremely Severe, not a UK sports climb grade.
The plate had been placed there by the 'Climbing Pixie' and there was a cartoon drawing showing this intrepid individual.
Apparently in elder days, people were hanged from the battlements down the line of the groove.
An atmospheric line.