Found on the back of a milestone on Shooters Hill, London. A milestone erected in the Century, to which a plate commemorating the the First World War battles of Ypres, and indicating the distance to Ypres has been attached.
At on July 1916 the Battle of the Somme started with explosion of 17 massive 'mines' underneath enemy territory. Lochnagar was the largest of these. It remains "The largest crater ever made by man 'in anger'".