 From the start of his Cairo posting Clarke learned the art of deception by trial and error. From mistakes during Camilla he learned to focus on what he wanted the enemy to do rather than on what he wanted them to think. From another early operation (K-Shell, the spreading of rumours about a new Allied super-shell which eventually petered out after the media picked up the story), he learned the value of conducting deception only when there was a clear objective, rather than because it was possible. From Bastion he discovered the difficulty of running a large deception on a short timescale. From these lessons Clarke evolved his principles of deception.
