Hutton made compasses that were hidden inside pens or tunic buttons, he used left-hand threads so that, if the Germans discovered them and the searcher tried to screw them open, they would just tighten.
Hutton made compasses, he used left-hand threads so that, if the Germans discovered them and the searcher tried to screw them open, they would just tighten. These compasses were hidden inside pens. These compasses were hidden inside tunic buttons.