LONDON 1944

Taking some time about my walk, aiming for the older, smooth barked trees. I found this Beech not far from the tower which has had a good deal of attention over the years. Plenty of discernible dates carved in the bark, the oldest possibly a 193* one, but I liked the "LONDON 1944" engraving on the right-hand trunk. 

What was the hill like in 1944 and who carved it? Why were they in Edinburgh?