With the scheme approved, Codner and Williams set to work. A vaulting horse was constructed from stolen timber, plywood with cigarette package wrappings used for the top. After a period of legitimate use, Codner and Williams started to dig a tunnel from inside the horse. One man was carried out in the horse and the tunnel started by digging a shaft, lined with plywood panels from Red Cross parcel boxes. After each session, care was taken to secure the top of the shaft and to replace the surface sand on top. The digger and the sand excavated were carried back into a hut and the sand disposed of. Initially Philpot assisted in disposing of the sand, but later on Codner and Williams asked him to join in the digging and become one of the escapers. Digging was a cramped job and sand was dragged back to the bottom of the shaft by the digger and then placed into bags for lifting and disposal. Only 12 bags per session were lifted. After a while, the team swapped to a four-cycle dig-and-lift scheme, where two men went out on the first trip and dug 36 bags of sand. For the next three trips, one man went out and recovered 12 bags each time. As the tunnel grew longer, a bowl and string were used for pulling the sand back. Although this was slightly slower (36 bags per cycle as opposed to 48 under the old system), it meant three shorter sessions and one longer one for the volunteers using the horse for vaulting, an important change as the number of volunteers was small and they were becoming tired.