What is a peel?

"Peel" was a term used for the towers or strongholds that the wealthier people in England live in. These "peel-towers" gave them better protections from raiding Scots.

We got the idea of a stronghold from the old peel- tower which stood some way down the valley. In grandfather's time, all the wealthier people lived in peel towers of that kind, because you never knew when the Scots might come pouring over the Border on one of their raiding expeditions. But there had been no such raids since I was born, and some of the local squires were giving up their "peels" and building ordinary houses.

Another use of the word "peel" was the way in which secret messages were transmitted. messages were written on a small slip of paper and hidden in a slit cut into the peel of an orange.

"That's a well-known method of transmitting messages. A tiny cut in the peel of an orange, say—slip in a small folded paper, send a basket of oranges to your friend, and there you are."