Can you suggest any other possible clues, aside from those actually given on page 169, whereby Tom could have determined whether or not the peel tower had been visited recently?

Tom notices fresh oil in the lock, mud on the steps, it looked as if the steps must have been scoured clean by a driving storm, horses had been there within a few days because there were hoof marks, rust had been rubbed of the rings, there was fresh corn on the floor.