What really grabbed my attention for this image was a very, very tall cherry picker that was working in the grounds of the prison. By the time I got up the hill to the canal to grab a picture, however, the cherry picker had gone off to other work and was nowhere to be seen.

But then I looked at the canal, and was surprised to see the strange textures in the water, caused by just-submerged ice. And when I saw the reflections of the tree, I knew I had a picture.