Over the following months Pierce and Agar created rough keys from the impressions they had taken. In April and May 1855 Agar would travel along the Folkestone route when Burgess was on duty—seven or eight trips in total—and would hone the keys until they worked smoothly and without effort. Pierce and Agar then separately visited the Shot Tower, Lambeth, where they obtained of lead shot. They also obtained courier bags, which could be strapped under a cloak, and carpet bags: these were to carry the lead shot onto the train, and the gold off it.