Ban the Bomb.

Many years ago, a branch appears to have fallen off this tree trunk, the wound has long since healed (approximately) and the tree has flourished.

We've been walking dogs past it for the last thirty five years and any changes have been so slow as to be un-noticeable. The scar has been scored with the "Ban the Bomb" logo from fifty years ago, which I guess dates both the fall of the branch and the graffito; it has also been used for target practice with an air gun and the pellets are still embedded in the dead wood. It is now quite difficult to make out the top arm of the symbol.