The inscription carved into the huge beech tree, which stands on a hill path in Gloucestershire, reads PM 10/9/13 MKN. Next month, this piece of vandalism – though I cannot see it as that now – will be 100 years old, which seems incredible for something probably done on the spur of the moment. I often wonder about PM and MKN – if their love lasted and whether both made it through the First World War, which broke out 11 months later, on Tuesday 4 August.

It seems likely that PM was a young man who dug his knife into the smooth surface of the already ancient tree, putting himself above the date and the initials of the girl of his dreams. It was a Wednesday, perhaps in the evening after they both had finished work, when this path is dappled with light from the west. I suspect they were together and that some kind of declaration or promise was made, which is why he carved the date so deep into the bark. I can't be sure about any of this, of course, but last week I toured four local war memorials to search for a PM, or a MKN, just in case the carver had put his initials second, and was pleased that I found neither. Perhaps both survived the war and lived happily further into the 20th century.

Looking at those war memorials is shocking because of the sheer numbers. It reminded me that today is the anniversary of Britain's declaration of war against Germany and that next year we will be marking the centenary to end all centenaries: 100 years since those boys began to leave the fields for the hell of Flanders....