by its name. Bushell took this so seriously that he threatened to court-martial anyone who even uttered the word "tunnel". Tom began in a darkened corner next to a stove chimney in hut 123 and extended west into the forest. It was found by the Germans and dynamited. Dick'''s entrance was hidden in a drain sump in the washroom of hut 122 and had the most secure trap door. It was to go in the same direction as Tom and the prisoners decided that the hut would not be a suspected tunnel site as it was further from the wire than the others. Dick was abandoned for escape purposes because the area where it would have surfaced was cleared for camp expansion. Dick was used to store soil and supplies and as a workshop.Harry, which began in hut 104, went under the Vorlager (which contained the German administration area), sick hut and the isolation cells to emerge at the woods on the northern edge of the camp. The entrance to "Harry" was hidden under a stove. Ultimately used for the escape, it was discovered as the escape was in progress with only 76 of the planned 220 prisoners free. The Germans filled it with sewage and sand and sealed it with cement. After the escape, the prisoners started digging another tunnel called George, but this was abandoned when the camp was evacuated. Tunnel construction The tunnels were very deep – about below the surface. They were very small, only square, though larger chambers were dug to house an air pump, a workshop and staging posts along each tunnel. The sandy walls were shored up with pieces of wood scavenged from all over the camp, much from the prisoners' beds (of the twenty or so boards originally supporting each mattress, only about eight were left on each bed). Other wooden furniture was also scavenged. Other materials were also used, such as Klim tin cans that had held powdered milk supplied by the Red Cross for the prisoners. The metal in the cans could be fashioned into various tools and items such as scoops and lamps, fuelled by fat skimmed off soup served at the camp and collected in tiny tin vessels, with wicks made from worn clothing. The main use of the Klim tins was for the extensive ventilation ducting in all three tunnels. As the tunnels grew longer, a number